Report of e.g. copper's courage (6)

I believe the answer is:

mettle

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'courage' is the definition.
(mettle is a kind of courage)

I don't understand the remainder of the clue.

(Other definitions for mettle that I've seen before include "Bravery" , "Quality" , "'Nerve, heart, courage (6)'" , "Inherent character - courage" , "Grit" .)

I've seen this clue in The Times.

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