Vehicle at all times needed for occupation (6)
I believe the answer is:
career
'for occupation' is the definition.
(career is a kind of occupation)
'vehicle at all times needed' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'at all times' becomes 'eer' (archaic or poetic word meaning ever or forever).
'needed' is a charade indicator (letters next to each other).
'car'+'eer'='CAREER'
(Other definitions for career that I've seen before include "Quick" , "Life's occupation" , "Move rapidly in progress through life" , "Whole of employment" , "Long-term occupation" .)