The followers stand here when assembled (9)
I believe the answer is:
adherents
'the followers' is the definition.
(adherent is a kind of follower)
'stand here when assembled' is the wordplay.
'when assembled' is an anagram indicator (I've seen this in other clues).
'stand'+'here'='standhere'
'standhere' with letters rearranged gives 'ADHERENTS'.
(Other definitions for adherents that I've seen before include "Supporters of neat herds" , "'Supporters, disciples (9)'" , "Followers" , "Supporters of neatherds" .)