What horses may do in pound (6)

I believe the answer is:

nicker

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'pound' is the definition.
(nicker can informally mean pound sterling)

I cannot understand how the remainder of the clue works.

(Other definitions for nicker that I've seen before include "Sound made by horse" , "GBP1 (slang)" , "thief" , "PS1 (slang)" , "Pound (slang)" .)

I've seen this clue in The Times.

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