Chap has one potato he is about to lose? (9)

I believe the answer is:

hesitater

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'chap has one potato he is about to lose?' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.

'he is about to lose?' is the wordplay.
'about' shows that the letters should be reversed in order.
'to lose?' becomes 'tater' (I can't justify this - if you can you should give a lot more credence to this answer).
'is' backwards is 'si'.
'he'+'si'+'tater'='HESITATER'

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(Another definition for hesitater that I've seen is " Proverbial loser".)

I've seen this clue in The Guardian.

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