Standards of those who stop things happening (7)
I believe the answer is:
I believe this clue is a double definition.
'standards' is the first definition.
(I know this)
'those who stop things happening' is the second definition.
(people who ban things)
'of' is the link.
(Other definitions for banners that I've seen before include "Long strips with messages hung in public places" , "Newspaper headlines or flags" .)