Social gathering on an island (7)
I believe the answer is:
reunion
I believe this is a triple definition!
'social' is the first definition.
(thesaurus)
'gathering' is the second definition.
(reunion is a kind of gathering)
'on' is a link.
'an island' is the third definition.
(I've seen this before)
(Other definitions for reunion that I've seen before include "Meeting; French island" , "Later meet-up" , "Meeting of a past group" , "part of France" , "Get-together of old friends" .)