Compared to our knock-down-drag-out four-parter on anagrams, best practices for containers are a walk in the park. We've also observed that they tend to be a neophyte constructor's least used tool (even though in published puzzles, they tend to rank second or third among clue types in frequency).
Containers work two ways — this around that or that into this. It's easy to imagine qualified indicators — such as surrounding or entering, respectively — but there is some fuzziness around some of the language's most common verbs.
Have at it
Does "this having that" mean TH(THAT)IS? We've bruited this and would say yes. Further, we don't think that it's an appropriate charade indicator — "this having that" doesn't mean THIS + THAT.
Ambiguous indicators are a good thing — breaking could signal anagram or insertion (aka "that into this"), for instance — but the problem is more settling on what just have's definition of "to hold/obtain" means in an "X having Y" context. That box has crackers; this is a container having cheese. "Having" pretty clearly denotes containing and, as such, we would recommend not using it as an adjacency indicator. If it means enveloping, it doesn't also mean appending.
We'd say the same thing about getting — yes, Poker Face getting a second season would mean that that second season is appended to the first, in the manner of an X + Y charade, but what it really means is that the Poker Face corpus is expanding — a container situation. Contrast with the more arithmetically linear adding — that one works for charades, and we wouldn't use it to mean "this around that."
So that's how containers and charades intersect — or, rather, don't intersect. We've come to adopt a bit of a bright line about this: Don't use a container word as a positional indicator for a charade.
But containers have a close neighbor we have to consider.
Almost all container indicators and also hidden indicators, excepting only those that are in the active voice. To wit:
Grassland to cover insect — PL(ANT)AIN ✅
Grassland covers insect — PL(ANT)AIN ✅
Grassland covering insect — PL(ANT)AIN ✅
Plantain to cover insect — plANTain ❌
Plantain covers insect — plANTain ✅
Plantain covering insect — plANTain ✅
Note that we don't have covered in those examples. Cryptic clues are a present tense endeavor, and in the above all of those conjugations of cover are serving as verbs. When you see a past-tense verb as an indicator, as you often will in anagrams — e.g. mixed media for AIMED — it's because it's really an adjective. So insect covered in grassland would be legit because it's part of an adjectival phrase.
With that in mind, let's talk about with.
For a very long time, with as a container indicator was verboten around these parts because jmsr525 couldn't identify a case of containment using the word with naturally, except in highly specific phrases like "with child." We consigned with to a charade indicator, pace adding above.
This changed recently when jmsr525 was explaining to his daughter that she had two cups and "this was her cup with milk." That certainly felt like a natural use case implying containment, but it opened up an even bigger can of worms. Or should I say … can with worms.
The problem is the word of. It seems clear that if you accept with as a container indicator, you must also accept of. It further follows that with and of should be hidden indicators.
That seems too much of a stretch to our ears. What we're dealing with is the different between containership (a cup [temporarily filled] with milk) and essence (the can's existence is tied up in the fact that it has worms in it; think also of Jimmy Buffett's shaker of salt). Putting that dilemma to your solvers feels like it makes parsing difficult without offering much of an a-ha; in other words, a big ask for little upside.
And so, going back to with, we have to DQ its container nature as well. You could say that 4(a) accompaniment and 4(b) inclusive of mean that with is both charade and container, but we hold fast to our principle that for the sake of cleanness and thus your solvers' happiness, those two categories shouldn't overlap.
Speaking of overlap: We also use with and of as means to connect wordplay and definition within the overall clue structure, should the surface not let the two parts be directly adjacent. (Specifically, the use cases of [wordplay] with [definition], [definition] with [wordplay], and [definition] of [wordplay] — but not [wordplay] of [definition] or, for that matter, [definition] of [definition].) So for our tastes, solvers are already overburdened considering those words without making a practice of a sneaky additional usage (and that's not even counting that those words might appear in the definition of the answer or the definition of other wordplay components).
Unlike most Tap The Sign ideals, however, it's more about being unfair than "wrong." When it comes to this sign, we'll tapp — two Ps because we're doing it very quietly.
A thought experiment to prepare you for our next TTS: Do words have clothes?