Broken trust restricting French art teacher once (7)

I believe the answer is:

tutress

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'teacher once' is the definition.
I can't judge whether this defines the answer.

'broken trust restricting french art' is the wordplay.
'broken' indicates anagramming the letters.
'restricting' is an insertion indicator.
'french art' becomes 'es' ('is' in French - 'art' can mean 'is' eg 'thou art').
'trust' with letters rearranged gives 'tutrs'.
'tutrs' placed around 'es' is 'TUTRESS'.

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I've seen this clue in The Telegraph.

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