"Boléro" composer (5)
I believe the answer is:
ravel
'bolero composer' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ravel that I've seen before include "Make more complicated - French composer, d. 1937" , "note-writer observed" , "French composer, Maurice (1875-1937)" , "Tangle or become tangled" , "Entangle - French composer, d. 1937" .)