Willing female (9)

I believe the answer is:

testatrix

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'willing female' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?

This is all the clue.

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(Other definitions for testatrix that I've seen before include "Woman willing" , "A woman who has made a will" .)

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

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