Suitably like diamonds? (3)

I believe the answer is:

red

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'like diamonds?' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

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(Other definitions for red that I've seen before include "See it and become angry" , "Left-wing" , "'If you see it, perhaps you're angry (3)'" , "Bloodshot" , "Carmine" .)

I've seen this clue in the Evening Standard.

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