Inspects cars including MOT finally (6)
I believe the answer is:
audits
'inspects' is the definition.
('audit' can be a synonym of 'inspect')
'cars including mot finally' is the wordplay.
'cars' becomes 'Audis' (Audi is a car manufacturer).
'including' is an insertion indicator.
'finally' suggests the final letters.
The final letter of 'mot' is 't'.
'audis' going around 't' is 'AUDITS'.
(Other definitions for audits that I've seen before include "Inspections by accountants" , "Balancing checks" , "Examination of accounts" , "examinations" , "Inspections of accounts" .)