Pharaoh in "The Ten Commandments" (7)
I believe the answer is:
'pharaoh in the ten commandments' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rameses that I've seen before include "Ancient king" , "Egyptian pharaoh" , "See Mars (anag) - Pharaoh" , "Name of several ancient Egyptian rulers - ear mess (anag)" , "Egyptian king" .)