Driving power of Corbynites! (8)
I believe the answer is:
momentum
I believe this is a double definition.
'driving power' is the first definition.
(I've seen this before)
'corbynites' is the second definition.
(I've seen this before)
'of' is the link.
(Other definitions for momentum that I've seen before include "driving power" , "Driving force, impetus" , "Impetus from motion" , "Corbynites" , "Impetus gained by a moving object" .)