Soprano Maria (6)
I believe the answer is:
callas
'soprano maria' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for callas that I've seen before include "Maria, Greco-American soprano" , "Coloratura soprano of Greek background" , "Great Greek American soprano" , "Maria - - , opera singer" , "Superb soprano of Greek background" .)