Diva (5,5)
I believe the answer is:
prima donna
'diva' is the definition.
(I know that diva can be written as prima donna)
This is the entire clue.
(Other definitions for prima donna that I've seen before include "(Over-sensitive) leading lady" , "Top female singer" , "temperamental sort" , "Leading lady, proverbially temperamental" , "opera star - with 2d" .)