Old maid? (5)

I think it could be either:

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wench

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This clue could be a double definition.

'old' is the first definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

'maid?' is the second definition.
(thesaurus)

Can you help me to learn more?

(Other definitions for wench that I've seen before include "An archaic girl" , "(Young) woman" , "Servant girl" .)

I've seen this clue in The Globe and Mail.

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