Religious female going backwards and forwards (3)

I believe the answer is:

nun

This clue is a double definition.

'religious female' is the first definition.
(I've seen this before)

'going backwards and forwards' is the second definition.

(Other definitions for nun that I've seen before include "Devout woman" , "Priory female" , "A palindromic lady in religious order" , "Woman in religious community" , "Woman with a habit" .)

I've seen this clue in The Times.

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