A man with depth inside a car (5)
I believe the answer is:
sedan
'a car' is the definition.
(sedan is a kind of car)
'a man with depth' is the wordplay.
'a man' becomes 'sean' ().
'with' means one lot of letters goes inside another.
'depth' becomes 'd' (abbreviation in geometry).
'sean' enclosing 'd' is 'SEDAN'.
'inside' acts as a link.
(Other definitions for sedan that I've seen before include "Old carrier chair for Danes" , "Once a mobile chair for Danes" , "Old carrying chair" , "Where Prussians defeated French" , "Andes (anag.)" .)