Vigour, zip (6)
I believe the answer is:
energy
I believe this clue is a double definition.
'vigour' is the first definition.
(I know that vigour can be written as energy)
'zip' is the second definition.
(I know that zip can be written as energy)
(Other definitions for energy that I've seen before include "Seventeen forty six defeat for Bonnie Prince Charlie" , "Vigour, vim, vitality" , "Vitality, power" , "Healthy capacity for vigorous activity" , "Strength, vitality" .)