Outstanding person who sings, a real prima donna! (9)

I believe the answer is:

superbrat

'a real prima donna' is the definition.
(both can mean a bratty performer)

'outstanding person who sings' is the wordplay.
'outstanding' becomes 'superb' (I've seen this in another clue).
'person who sings' becomes 'rat' (someone who 'sings' to the authorities).
'superb'+'rat'='SUPERBRAT'

(Another definition for superbrat that I've seen is " Infuriatingly, he served".)

I've seen this clue in The Times.

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