Bit of Bizet (4)
I believe the answer is:
aria
'bit of bizet' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for aria that I've seen before include "Type of song" , "Puccini item" , "Song from an opera (4)" , "Opera solo" , "Vocal solo in a cantata etc" .)