Fill with enthusiasm to revolutionise green lives on Earth (8)
I believe the answer is:
energise
'fill with enthusiasm' is the definition.
(energise can mean to enthuse or inspire)
'revolutionise green lives on earth' is the wordplay.
'revolutionise' indicates anagramming the letters (I've seen 'revolutionised' mean this).
'lives' becomes 'is' ('be' can be a synonym of 'live').
'on' is a charade indicator (letters next to each other).
'earth' becomes 'E'.
'green' with letters rearranged gives 'energ'.
'energ'+'is'+'e'='ENERGISE'
'to' is the link.
(Other definitions for energise that I've seen before include "give vigour" , "Motivate" , "Activate" , "Give power to" , "Give vitality to" .)