God reveals that bishop has departed (4)
I believe the answer is:
ares
'god' is the definition.
(Greek god of war)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for ares that I've seen before include "Belligerent god" , "figure of worship" , "Olympian" , "War-god" , "Land measures" .)