Drive and energy -- oddly very low in reverse (5)
I believe the answer is:
vroom
'drive and energy' is the definition.
(powerful noise of a car)
'oddly very low in reverse' is the wordplay.
'oddly' means one should take alternating letters (letters in the odd-numbered positions are used).
'low' becomes 'moo' (both can mean to make the noise of a cow).
'in reverse' says the letters should be written backwards.
The alternating letters of 'very' are 'vr'.
'moo' backwards is 'oom'.
'vr'+'oom'='VROOM'
(Other definitions for vroom that I've seen before include "Exclamation imitating a revving car" , "Fast-moving car noise" , "roar away" , "(Of engine) make roaring sound (colloq.)" , "loud engine noise" .)