Ancient Egyptian god who was ruler of the underworld and judge of the dead (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
osiris
(Other definitions for osiris that I've seen before include "Egyptian god - sis or I (anag)" , "dead judge?" , "Husband of Isis, father of Horus - sis or I (anag)" , "Egyptian deity" , "underworld boss" .)