Recurring theme or idea (5)
I believe the answer is:
motif
This clue is a double definition.
'recurring theme' is the first definition.
(I've seen this in another clue)
'idea' is the second definition.
(motif is a kind of idea)
(Other definitions for motif that I've seen before include "sign" , "Characteristic theme" , "Logo -- pattern" , "Main theme in music" , "Theme or recurring feature in music or writing" .)