Causes to see red as green when changing (7)
I believe the answer is:
enrages
'causes to see red' is the definition.
'as green when changing' is the wordplay.
'when changing' indicates an anagram.
'as'+'green'='asgreen'
'asgreen' with letters rearranged gives 'ENRAGES'.
(Other definitions for enrages that I've seen before include "Works up" , "Makes red" , "Makes furious" , "Infuriates" , "As green changes it makes one angry" .)