Move to the right alternatives for energy, in hindsight (3)
I believe the answer is:
gee
'move to the right' is the definition.
(command given to a horse)
'alternatives for energy in hindsight' is the wordplay.
'alternatives for' means one should take alternating letters (alternate letters are selected).
'in hindsight' says the letters should be written in reverse (hindsight is looking back).
The alternate letters of 'energy' are 'eeg'.
'eeg' in reverse letter order is 'GEE'.
(Other definitions for gee that I've seen before include "Mild exclamation" , "provided by substitute for ginger?" , "Urge horse - expression of surprise" , "Golly" , "Gosh" .)