Run second vehicle (7)
I believe the answer is:
scamper
'run' is the definition.
(I know that scamper is a type of run)
'second vehicle' is the wordplay.
I cannot really understand how this works, but
'second' could be 's' (common abbreviation) and 's' is present in the answer.
'vehicle' could be 'camper' (camper is a kind of vehicle) and 'camper' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for scamper that I've seen before include "Beetle" , "Run about briskly" , "Scurry, scuttle" , "Run quickly and lightly" , "Proceed hurriedly" .)