Stage solo (4)
I believe the answer is:
aria
'stage solo' 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 "Opera solo" , "Operatic air" , "Operatic vocal" , "Nessun Dorma, for example" , "Song such as "Your Tiny Hand is Frozen"" .)