The worship of false gods (8)
I believe the answer is:
idolatry
'the worship of false gods' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for idolatry that I've seen before include "Dilatory way of worshipping" , "Icon worship" , "bowing down before a goddess?" , "reverence" , "Extreme admiration" .)