Might one steal a pound sterling (6)

I believe the answer is:

nicker

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'pound sterling' is the definition.
'nicker' can be an answer for 'pound' (nicker can informally mean pound sterling). I'm unsure of the 'sterling' bit.

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for nicker that I've seen before include "One steals" , "thief" , "One stealing" , "Money" , "PS1 (slang)" .)

I've seen this clue in The Sunday Times.

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