Vocal showcase (4)
I believe the answer is:
aria
'vocal showcase' 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 "Opera solo" , "Song such as "Your Tiny Hand is Frozen"" , "Summertime perhaps" , "Song for solo voice from an oratorio, cantata etc" , "part of opera, maybe" .)