Friend, a nuisance ultimately abandoning capital (3)

I believe the answer is:

bud

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'friend' is the definition.
(short for buddy)

I cannot understand how the rest of the clue works.

(Other definitions for bud that I've seen before include "American beer" , "Small pre-flower knob - nip it" , "Opening flower" , "Small pre-flower knob on plant" , "Shoot, sprout" .)

I've seen this clue in The Times.

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