A play, perhaps? Or gambit?
As in, given a certain context, you might execute a play from a playbook, or employ a certain gambit.
Both fallsfall somewhere between strategy and tactics, I'd say. Preplanned, but contingent on the situation. Rehearsed tactics, really.
And both are short (which, I gather from your comments, is what you're looking for). Of course, "play" in particular is also a word with many different meanings, so it may confuse.
Scheme or ploy would be other possibilities, though both are often used when describing more nefarious trickery.
Strategem is a synonym for either of these, by the way.