Debauch (4)
I believe the answer is:
orgy
'debauch' is the definition.
(I know that debauch can be written as orgy)
This is all the clue.
(Other definitions for orgy that I've seen before include "Binge" , "Drunken revel" , "Drunken revelry" , "Very intimate get-together" , "Wild overindulgent party" .)