Possible opposite of 'hen' (4)

I believe the answer is:

stag

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'possible opposite of hen' is the definition.
The answer and definition can be both animals as well as being singular nouns.
Perhaps there's an association between them I don't understand?

This is all the clue.

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(Other definitions for stag that I've seen before include "Without women" , "Male-only" , "Sort of party" , "Antlered animal" , "Hart" .)

I've seen this clue in the Evening Standard.

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