Cutting back, setting cost for policeman? Not right (9)

I believe the answer is:

coppicing

'cutting back' is the definition.

'cost for policeman? not right' is the wordplay.
I cannot really see how this works, but
'policeman?' could be 'cop' (cop is a kind of policeman) and 'cop' is present in the answer.
This may be the basis of clue (or it may be nonsense).

'setting' is the link.

I've seen this clue in The Times.

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