Motive power (6)
I believe the answer is:
energy
(Other definitions for energy that I've seen before include "Exertion of force" , "Vitality, power" , "Vitality, get-up-and-go" , "Capacity for action" , "Vigour, animation" .)
I believe the answer is:
energy
(Other definitions for energy that I've seen before include "Exertion of force" , "Vitality, power" , "Vitality, get-up-and-go" , "Capacity for action" , "Vigour, animation" .)