Take apart to examine and repair if necessary (8)
I believe the answer is:
overhaul
'take apart to examine and repair if necessary' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for overhaul that I've seen before include "Outpace or renovate" , "Check-up" , "Check and repair - pass" , "Take apart to examine and repair if necessary" , "Inspect and repair" .)