Girl unaffected by revolution (4)

I believe the answer is:

anna

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This could be a double definition.

'girl' is the first definition.

'unaffected by revolution' is the second definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

Can you help me to learn more?

(Other definitions for anna that I've seen before include "worth very little in India" , "Miss Karenina" , "Former Indian coin; girl's name" , "Old Indian coin - girl's name" , "Book by Tolstoy" .)

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