The offence of the offender will extend to all the other members of the clan.
“if one finger brought oil it soiled the others” means that just one oily finger will taint all the other fingers with oil; another way to look at it is that the dirt of one finger will extend to the other fingers if you don't clean it first. In other words the phrase “if one finger brought oil it soiled the others” is a metaphorical way of saying that if left unpunished, the sin of one person extend to the whole community. We can confirm this by replacing finger with member of the clan and oil whit offence in the phrase: If one offender member of the clan brought offence (to the great goddess) it soiled the others (members of the clan).
