Bacchanalian party
I believe the answer is:
orgy
'bacchanalian party' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for orgy that I've seen before include "Wild, debauched gathering" , "Drunken revel" , "Debauched party" , "Rumpy-pumpy party" , "Bacchanal" .)