Infuriate a Green liberal (6)
I believe the answer is:
enrage
'infuriate' is the definition.
(I've seen this before)
'a green liberal' is the wordplay.
'liberal' indicates an anagram.
'a'+'green'='agreen'
'agreen' is an anagram of 'ENRAGE'.
(Other definitions for enrage that I've seen before include "Drive to anger" , "French revolutionary group" , "put people's back up" , "Incense" , "Make violently angry" .)