Revolutionary vehicle (5)
I believe the answer is:
cycle
This clue could be a double definition.
'revolutionary' is the first definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'vehicle' is the second definition.
(cycle is a kind of vehicle)
Can you help me to learn more?
(Other definitions for cycle that I've seen before include "Periodic sequence" , "Repeated series of events" , "Series of works; bike" , "Come round" , "go around" .)