Bent on playing the old soldier? (6)

I believe the answer is:

arched

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'bent' is the definition.
(arching is a kind of bending)

I don't understand the rest of the clue.

(Other definitions for arched that I've seen before include "Curved up in the centre" , "Bent" , "Bowed, curved" , "Raised in the centre" , "Raised in the middle" .)

I've seen this clue in the Evening Standard.

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