Omnipotent one reversing the waterway (4)
I believe the answer is:
zeus
'one reversing the waterway' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for zeus that I've seen before include "Celestial ruler" , "Supreme god of Ancient Greece" , "God whose statue was one of the Seven Wonders" , "Divine son of Cronos and Rhea" , "Greatest ancient Greek god" .)