Vehicle not returning package (6)
I believe the answer is:
carton
'package' is the definition.
(thesaurus)
'vehicle not returning' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle**).
'returning' says the letters should be written in reverse.
'not' back-to-front is 'ton'.
'car'+'ton'='CARTON'
(Other definitions for carton that I've seen before include "Container for food or liquid" , "Box made of cardboard" , "Flapped cardboard box" , "Dickensian hero" , "fictional lawyer" .)