One taking someone off in spare motor, breaking down (12)

I believe the answer is:

impersonator

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'one taking someone off' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.

'in spare motor breaking down' is the wordplay.
'breaking down' indicates an anagram.
'in'+'spare'+'motor'='insparemotor'
'insparemotor' is an anagram of 'IMPERSONATOR'.

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(Other definitions for impersonator that I've seen before include "Mimic" , "One's often acting" , "he takes off" , "One pretending to be another" , "ape" .)

I've seen this clue in The Telegraph.

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