God over Lord exists (6)
I believe the answer is:
osiris
'god' is the definition.
(I know that Osiris is a type of dying-and-rising deity)
'over lord exists' is the wordplay.
'over' becomes 'o' (cricket abbreviation).
'lord' becomes 'sir' (both are respectful terms of address for a man).
'exists' becomes 'is' (if something 'is', it exists).
'o'+'sir'+'is'='OSIRIS'
(Other definitions for osiris that I've seen before include "Egyptian god, father of Horus" , "Egyptian deity" , "underworld boss" , "Egypt. god of dead" , "dead judge?" .)