Jazz lick (4)
I believe the answer is:
riff
'jazz lick' 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 "Berber - repeated jazz phrase" , "Short repeated jazz figure" , "Short series of chords in jazz" , "Moroccan - musical phrase" , "Short repeated phrase in popular music or jazz" .)