Crossword Genius

Endorsement given by diva in performing with alto (10)

Ross

I believe the answer is:

validation

'endorsement' is the definition.
(thesaurus)

'diva in performing with alto' is the wordplay.
'performing with' indicates anagramming the letters (the letters move around or 'perform').
'diva'+'in'='divain'
'divain' mixed up with 'alto' makes 'VALIDATION'.

'given by' is the link.

(Another definition for validation that I've seen is " Confirmation (of the truth of something)".)

I've seen this clue in The Times.
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