Frigid acceptance of explanation by the sound of it (3)

I believe the answer is:

icy

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'frigid' is the definition.
('icy' can be a synonym of 'frigid')

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

(Other definitions for icy that I've seen before include "frozen over!" , "Freezing cold" , "Very cold, unfriendly" , "Freezing and slippy" , "Distant - freezing" .)

I've seen this clue in The Globe and Mail.

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