Diamonds kept in the fridge? (3)

I believe the answer is:

ice

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'diamonds' is the definition.
(slang term for diamonds)

I cannot understand how the rest of the clue works.

(Other definitions for ice that I've seen before include "Solid water" , "If it's thin, skating on it can be dangerous" , "Diamond" , "Do cake decoration" , "Skating surface" .)

I've seen this clue in the Evening Standard.

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