a song of ice and fire book 1 question.

Im a little confused on a term i ran into. As far as i know a septon is like a priest and a sept is a place of prayer. Please clear this up if im incorrect. On page 181 donal noye the armouror of castle black breaks up a fight between jon, grenn,toad and the unknown rappers. Donal says other people have it harder then him and that the boy jeren is a "septons get" what exactly is a septons get?