Drive back that you spoil (3)

I believe the answer is:

mar

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'you spoil' is the definition.
'mar' can be an answer for 'spoil' (I've seen this before). I'm not sure about the 'you' bit.

'drive back' is the wordplay.
'drive' becomes 'ram' (RAM drive on a computer).
'back' says the letters should be written in reverse.
'ram' backwards is 'MAR'.

'that' acts as a link.

Can you help me to learn more?

(Other definitions for mar that I've seen before include "'Impair, spoil (3)'" , "Disfigure" , "when spring growth starts?" , "Ram into and spoil" , "Blight" .)

I've seen this clue in the Evening Standard.

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