Card for social organisation (4)
I believe the answer is:
club
This clue is a double definition.
'card' is the first definition.
(the clubs are a playing card suit)
'social organisation' is the second definition.
(I've seen this before)
'for' is the link.
(Other definitions for club that I've seen before include "nightspot" , "wood, perhaps" , "Golf requisite" , "beat" , "Bat - society" .)