Unfortunately Cinderella got fat whilst transgressing (9,7)

I believe the answer is:

flagrante delicto

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'unfortunately cinderella got fat whilst transgressing' is the definition.
I can't judge whether this defines the answer.

'unfortunately cinderella got fat' is the wordplay.
'unfortunately' indicates anagramming the letters (a bad or unfortunate spelling).
'cinderella'+'got'+'fat'='cinderellagotfat'
'cinderellagotfat' with letters rearranged gives 'FLAGRANTE DELICTO'.

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I've seen this clue in The Times.

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