One may put one's foot down using this vehicle (7)
'vehicle' is the definition.
(scooter is a kind of vehicle)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for scooter that I've seen before include "Traveller", "one makes off quickly", "Light motorcycle", "it may need physical boost", "Vehicle and child's toy".)