Thorough repair (8)
I believe the answer is:
overhaul
'thorough repair' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for overhaul that I've seen before include "Outpace or renovate" , "Renovate, maintain" , "Pass - examination" , "Examine and improve condition" , "Recondition" .)