Go both ways (3)
I believe the answer is:
pep
I believe this clue is a double definition.
'go' is the first definition.
(both can mean energy or vitality)
'both ways' is the second definition.
(Other definitions for pep that I've seen before include "savings plan" , "Energy or enthusiasm" , "Energy, zip" , "Energy, liveliness" , "Vim and vitality" .)