Conscious of a revolutionary green source of energy (5)
I believe the answer is:
aware
'conscious of' is the definition.
(thesaurus)
'a revolutionary green source of energy' is the wordplay.
'revolutionary' is a reversal indicator.
'green' becomes 'raw' ('raw' can be a synonym of 'green'**).
'source of' indicates taking the first letters.
The initial letter of 'energy' is 'e'.
'raw' backwards is 'war'.
'a'+'war'+'e'='AWARE'
(Other definitions for aware that I've seen before include "Acquainted with or mindful of" , "Acquainted with or conscious of" , "Conscious or having knowledge of" , "Apprised or informed" , "Knowing (of something)" .)