Cup that's cracked set aside, milk initially seeping through (9)

I believe the answer is:

demitasse

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'cup' is the definition.
(I know that demitasse is a type of coffee cup)

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

(Other definitions for demitasse that I've seen before include "Coffee-cup" , "little cup" , "Small cup for black coffee" .)

I've seen this clue in The Telegraph.

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