Copper nabbing Oscar, hollow rotten process which stands out (5)

I believe the answer is:

cornu

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'copper nabbing oscar hollow rotten process which stands out' is the definition.
The definition suggests a singular noun which matches the answer.

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(Other definitions for cornu that I've seen before include "In anatomy, any horn-shaped structure" , "Hornblower may want it?" , "Outgrowth" .)

I've seen this clue in The Sunday Times and The Times.

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