A fool, but at least he can hold his drink (3)

I believe the answer is:

mug

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'a fool' is the definition.
(I know that chump can be written as mug)

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

Can you help me to learn more?

(Other definitions for mug that I've seen before include "Drinking vessel for one easily deceived" , "simpleton" , "person's face" , "Drinking vessel or foolish fellow" , "One easily duped" .)

I've seen this clue in the Evening Standard.

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