Crimson vehicle belonging to me (7)
I believe the answer is:
carmine
'crimson' is the definition.
('carmine' can be a synonym of 'crimson')
'vehicle belonging to me' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'belonging to me' becomes 'mine' (I've seen this before).
'car'+'mine'='CARMINE'
(Other definitions for carmine that I've seen before include "Crimson pigment" , "Bright red" , "Vivid red colour" .)