Switch stance on gender identity (9)

I believe the answer is:

transpose

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But I can't explain it at all! Could you help me understand?

(Other definitions for transpose that I've seen before include "7 down (anag)" , "Write (music) into different key" , "Change to a different key" , "Adjust key" , "Cause to change places" .)

I've seen this clue in The Sunday Times.

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