Beat up with a kitchen tool (5)

I believe the answer is:

whisk

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'beat up' is the definition.
(thesaurus)

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

(Other definitions for whisk that I've seen before include "Whipping utensil" , "Kitchen mixer" , "Beat to a froth" , "Beat briskly" , "Egg beater" .)

I've seen this clue in the Evening Standard.

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