Get cold fast (5)

I believe the answer is:

nippy

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'fast' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for nippy that I've seen before include "Quick; chilly" , "progressing rapidly" , "active" , "Rather cold" , "Frosty - quick" .)

I've seen this clue in The Daily Express.

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