Diamonds could be made to fit (4)

I believe the answer is:

suit

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'fit' is the definition.
(suiting is a kind of fitting)

I don't understand how the rest of the clue works.

(Other definitions for suit that I've seen before include "Do as you please!" , "Eg, hearts or clubs" , "Diamonds, for example" , "Legal action - courtship" , "clubs, for example" .)

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

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