Failing student admitted to settling a debt (7,2)

I believe the answer is:

playing up

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'failing student admitted to settling a debt' is the definition.
I can't tell whether this defines the answer.

'failing student admitted to settling' is the wordplay.
'failing student' becomes 'l' (as in L-plates for learner drivers. I am not sure about the 'failing' bit.).
'admitted to' indicates putting letters inside.
'settling' becomes 'paying up' (paying up is a kind of settling).
'l' going inside 'payingup' is 'PLAYING UP'.

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I've seen this clue in The Daily Express.

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