Theme of some crosswords (but not this one) that involves entering multiple letters in a single square (5)

I believe the answer is:

rebus

(Other definitions for rebus that I've seen before include "Visual wordplay - Rankin's inspector" , "Puzzle where pictures represent syllables and words" , "Word-picture puzzle" , "Ian Rankin's Scottish detective" , "Problem" .)

I've seen this clue in The Washington Post.

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