Jazz motif (4)
I believe the answer is:
riff
'jazz motif' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for riff that I've seen before include "Short repeated phrase in popular music or jazz" , "Short series of chords in jazz" , "bit of music" , "Moroccan - musical phrase" , "Berber - repeated jazz phrase" .)