It's exactly according to form (7,3)

I believe the answer is:

perfect fit

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'it's exactly according' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'to form' is the wordplay.
'to' becomes 'perfect' (I am not sure about this - if you are sure you should believe this answer much more).
'form' becomes 'fit' (fitting is a kind of forming).
'perfect'+'fit'='PERFECT FIT'

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I've seen this clue in The Globe and Mail.

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