Yes, zep is a Scrabble word!
...and is worth 14 points in Scrabble, and 15 points in Words with Friends
zep
Noun
1. A large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States
What Scrabble words can I make with the letters in zep?
2 Letter Words