That man in violent slide reversing car (6)
I believe the answer is:
wheels
'car' is the definition.
(wheels can informally mean a car)
'that man in violent slide reversing' is the wordplay.
'that man' becomes 'he' ('he' refers to a man).
'in' means one lot of letters goes inside another.
'violent slide' becomes 'slew' (slew can mean a sliding movement in a vehicle).
'reversing' says the letters should be written in reverse.
'slew' back-to-front is 'wels'.
'he' inserted inside 'wels' is 'WHEELS'.
(Other definitions for wheels that I've seen before include "Spins on an axis" , "Circular frames with spokes" , "Personal transport" , "turns round" , "Vehicle" .)