Deep sea carbon in a green revolution (7)
I believe the answer is:
oceanic
'deep sea' is the definition.
(thesaurus)
'carbon in a green revolution' is the wordplay.
'carbon' becomes 'C' (chemical symbol).
'green' becomes 'eco' (eco-friendly).
'revolution' says the letters should be written backwards.
'c'+'in'+'a'+'eco'='cinaeco'
'cinaeco' back-to-front is 'OCEANIC'.
(Other definitions for oceanic that I've seen before include "Relating to great seas" , "Relating to large areas of sea" , "Pelagic" , "Relating to large areas of water" , "Pertaining to the sea" .)