Money -- a nicker? (6)

I believe the answer is:

copper

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'money' is the definition.
(I have seen 'Little money' mean 'copper' so perhaps 'money' could also mean 'copper')

I can't explain the remainder of the clue.

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(Other definitions for copper that I've seen before include "detector?" , "Metal - police officer" , "old tub" , "Element; butterfly" , "Metal for slang policeman" .)

I've seen this clue in The Telegraph.

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