Diva's piece (4)
I believe the answer is:
aria
'diva's piece' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aria that I've seen before include "part of opera, maybe" , "Vocal solo in a cantata etc" , "Operatic solo, duet, etc" , "Opera solo" , "Operatic part" .)