Wild party organised by outsiders (4)
I believe the answer is:
orgy
'wild party' is the definition.
(orgy can mean a boisterous party)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for orgy that I've seen before include "riot" , "Drunken revelry" , "Depraved scene" , "Wild revel" , "Unrestrained revel" .)