One opposing extraordinary action, Conservative must go (4)
I believe the answer is:
anti
'one opposing' is the definition.
(prefix meaning 'opposing')
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for anti that I've seen before include "One who is against (something)" , "Hostile" , "'No' voter" , "one opposing?" , "Against, informally" .)