Supporter finding witty remark after Sunak's first to resign (4)
I believe the answer is:
ally
'supporter' is the definition.
(I've seen this in another clue)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ally that I've seen before include "Friend in time of need" , "State formally cooperating with another" , "He fights on your side" , "A friendly and reliable country" , "Cooperating country" .)