Come across and congregate (4)
I believe the answer is:
meet
I believe this is a double definition.
'come across' is the first definition.
('meet' can be a synonym of 'come across')
'congregate' is the second definition.
(thesaurus)
'and' acts as a link.
(Other definitions for meet that I've seen before include "Come face to face - it is fitting" , "Come face to face with - it is proper" , "See 24" , "Deal with - encounter" , "Touch; suitable (arch.)" .)