Females said to appear twice in tutus (4)

I believe the answer is:

ewes

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

I cannot understand how the rest of the clue works.

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(Other definitions for ewes that I've seen before include "Female sheep" , "wool producers" , "She-sheep" , "farm animals" , "Females in the flock" .)

I've seen this clue in the Evening Standard.

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