Celebrated US-born soprano of Greek parentage (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
callas
(Other definitions for callas that I've seen before include "Noted late soprano of Greek background" , "Maria - - , opera singer" , "Maria ..., great diva of Greece" , "Greek diva" , "Superb soprano of Greek background" .)