Injunction makes group finish early (3)
I believe the answer is:
ban
'injunction' is the definition.
(I've seen this in other clues)
'group finish early' is the wordplay.
'group' becomes 'bank' (bank is a kind of group).
'finish early' means to remove the last letter (I've seen 'finished early' mean this (the word finishes earlier than normal)).
'bank' with its last letter taken away is 'BAN'.
'makes' acts as a link.
(Other definitions for ban that I've seen before include "Officially prohibit" , "'Forbid, prohibit (3)'" , "Bar, prohibition" , "Exile" , "the calling of young vassals" .)