Alive? No colder (6)

I believe the answer is:

aswarm

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'alive?' is the definition.
Both the answer and definition are adjectives.
Perhaps there's an association between them I don't understand?

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

Can you help me to learn more?

(Other definitions for aswarm that I've seen before include "crowds everywhere" , "Crawling" , "Teeming" , "Crowded" , "Like bees often are" .)

I've seen this clue in The Times.

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