From Clue 1, Ruthie, Orwell and the Black Olives were all three medium orders. From Clue 3, Norm and Keats both ordered larges, so the 5 people are
Ruthie, Orwell, Black Olive orderer,Norm and Keats
From Clue 5, someone ordered a large Guacamole, but not Jethro. It has to be either Keats or Norm, as they are the only ones ordering larges. Keats is not Deanna (clue 3), Norm (clue 3) or Ruthie (clue 1), so Keats is either Jethro or Paula. If Keats is Jethro, then Norm has to have the Large Guacamole. Since Quint has pepperoni, Quint is not Norm. Quint then, is a woman, so the women have pepperoni, jack cheese and chislic. This means that the men have guacamole and black olive. This is impossible, as the men both have larges. Thus, Jethro cannot be Keats - -Paula is Keats.
Now, either Paula or Norm has the Large Guacamole. If Norm, then he cannot be Quint (clue 2), Orwell(clue 1),Ingals (clue 6), or Keats, so he is Bones. This means that Paula Keats and Norm Bones have the larges, while Orwell, Ruthie and black olives are medium. Quint would then have to be Ruthie, who would have pepperoni, and Ingalls would have the Black Olive. This is impossible, because Clue 4 tells us that 2 of the three women had Chislic and Monterey Jack. So, we now know that Paula Keats had the Large Guacamole.
Women therefore have Guacamole,Cheese and Chislic, Men have Black Olive and Pepperoni. Jethro then has Black Olive, and Norm is Quint and has Pepperoni. Ruthie is Ingalls, leaving Deanne to be Orwell. Jethro is Bones. Ingals didn't have the cheese (Clue 6), so Deanne had the cheese and Ruthie had the chislic.
In summary,
Ruthie Ingalls Medium Chislic
Deanne Orwell Medium Monterey Jack
Jethro Bones Medium Black Olive
Norm Quint Large Pepperoni
Paula Keats Large Guacamole