Don't stop vehicle: run that (5,2)
I believe the answer is:
carry on
'don't stop' is the definition.
(I've seen this before)
'vehicle run that' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'run' becomes 'r' (cricket abbreviation).
'that' becomes 'yon' (archaic term meaning 'that').
'car'+'r'+'yon'='CARRY-ON'
(Other definitions for carry on that I've seen before include "Misbehave badly" , "The palaver" , "song and dance" , "Proceed" , "film series" .)