Possible Clues:

• A name for the Thames at Oxford and upstream
• Osiris' spouse
• Are, perhaps, a single deity
• "It depends on what the definition of ___"
• Si Si - she's an Egyption goddess
• Are, perhaps, one goddess from Egypt - or from Oxford
• Egyptian goddess - the Thames at Oxford
• Wife/sister of Osiris
• Is coming at the double from Egypt to Oxford
• Deity has two lives