Relating to living in groups (6)
I believe the answer is:
social
'relating to living in groups' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for social that I've seen before include "Public servant caring for the underprivileged" , "Liking companionship" , "Of society or its organisation" , "Living in an organised community in Licosa" , "Enjoying companionship" .)