Car not entirely unfashionable? Wrong in green (9)
'car' is the definition.
(limousine is a kind of car)
'not entirely unfashionable? wrong in green' is the wordplay.
'not entirely' means to remove the last letter.
'unfashionable?' becomes 'out' (similar in meaning).
'wrong' becomes 'sin' (I've seen this before).
'in' is an insertion indicator.
'green' becomes 'lime' (I've seen this before).
'out' with its last letter taken away is 'ou'.
'ousin' placed into 'lime' is 'LIMOUSINE'.
(Other definitions for limousine that I've seen before include "Form of transport", "Luxury car", "Large luxurious car", "vehicle", "big car".)