Overused theme (5)
I believe the answer is:
trope
'overused theme' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for trope that I've seen before include "Word or expression used in a figurative way" , "Figurative use of a word or expression; motif" , "metaphor, perhaps" , "Figure of speech - or pet (anag)" , "ironical expression" .)