The hard stuff one may keep in the kitchen (5)

I believe the answer is:

steel

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'the hard stuff' is the definition.
(I've seen this in another clue)

I don't understand the rest of the clue.

(Other definitions for steel that I've seen before include "Mixture of carbon and iron" , "Knife-sharpener" , "Determination, metal" , "Hard, strong, grey alloy" , "Iron/carbon alloy" .)

I've seen this clue in the Evening Standard.

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