How to complain about hard water (5)

I believe the answer is:

icily

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'how' is the definition.
Both the answer and definition are adverbs. Perhaps there's a link between them I don't understand?

I cannot understand how the remainder of the clue works.

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(Other definitions for icily that I've seen before include "Without feeling" , "In a cold manner" , "in unfriendly way" , "In a frosty manner" , "In a cool manner" .)

I've seen this clue in the Evening Standard.

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