Twosome, left to go away in car (5)
I believe the answer is:
coupe
'car' is the definition.
(I know that coupe is a type of car)
'twosome left to go away' is the wordplay.
'twosome' becomes 'couple' (synonyms).
'left' becomes 'L' (common abbreviation).
'to go away' is a deletion indicator.
'couple' with 'l' taken out is 'COUPE'.
'in' acts as a link.
(Other definitions for coupe that I've seen before include "Car with two front seats and a luggage compartment" , "Two-door car" , "Car; dessert glass" , "Car with just two doors and two front seats" , "Type of car; dish" .)