Animals that kill in the mountains? (4)

I believe the answer is:

cats

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'animals' is the definition.
(cats are animals)

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

(Other definitions for cats that I've seen before include "Siamese, Persian etc" , "Some 6 Downs" , "Feline musical by Andrew Lloyd Webber" , "Popular musical" , "Musical from TS Eliot" .)

I've seen this clue in the Evening Standard.

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