One packing up pugilism? (5)

I believe the answer is:

boxer

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'one packing' is the definition.
(someone boxing things up)

I cannot understand how the rest of the clue works.

(Other definitions for boxer that I've seen before include "Pugilist - dog" , "Breed of stocky short-haired dog" , "Dog - fighter" , "canine" , "Pug - dog" .)

I've seen this clue in the Evening Standard.

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