Composition for nine musicians (5)
I believe the answer is:
nonet
'composition for nine musicians' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nonet that I've seen before include "Tenon (anag.)" , "Piece for nine performers" , "Instrumental group of nine players" , "Work for nine players" , "Piece for nine musicians" .)