A climber, being a sort of nut (5)

I believe the answer is:

betel

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'nut' is the definition.
(I've seen this in another clue)

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

(Other definitions for betel that I've seen before include "Plant leaf chewed in the East" , "Asian feather palm" , "Palm with nuts for chewing" , "stimulatingly chewed in Asia" , "leaves to chew" .)

I've seen this clue in the Evening Standard.

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