Bar supporters: it would be unfair to move them (9)
I believe the answer is:
goalposts
This clue is a double definition.
'bar supporters' is the first definition.
(posts holding up the bar of a goal)
'it would be unfair to move them' is the second definition.
('moving the goalposts' is changing rules unfairly)
(Other definitions for goalposts that I've seen before include "sticks" , "Football uprights" , "One aims to score between them" , "more than one upright" .)