Jazz band (4)
I believe the answer is:
trio
'jazz band' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for trio that I've seen before include "Group of Magi?" , "Band of three" , "(Composition for) three performers" , "Piece for three players" , "Beethoven's 'Archduke': famous piece written for this ensemble" .)