What culinary element in Wellington beef, also found in pizza, does this dish feature?

I've looked everywhere and I cant find it. I need the answer to complete an enigma from a book a bought a week ago. The only hint that the book gives is that the culinary element or ingredient finishes in st and has 3 letters before st; so its _ _ _st. I need the other three letters.

Public Comments

1. crust Beef wellington is beef and other filling wrapped in dough (crust), and pizza is made on a crust.
2. yeast? to make the bread, or crust. Maybe it's actually crust.
3. The dough!! Beef wellington is wrapped in the same dough as a pizza crust is made...lol That was an easy one..lol YEAST!!!!
4. A Beef Wellington is a fillet mignon wrapped in puff pastry. You could be thinking of a pastry CRUST. Have added an address about the history of the meal. Sounds Good.