Licentious revelry (4)
I believe the answer is:
orgy
'licentious revelry' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for orgy that I've seen before include "Rumpy-pumpy party" , "Drunken revelry" , "Excess" , "Unrestrained revel" , "Wild, debauched gathering" .)