I'm unclear about your question. From http://effbot.org/tkinterbook/entry.htm#patterns, it seems you just need to do an assignment after you called the delete. To add entry text to the widget, use the insert method. To replace the current text, you can call delete before you insert the new text.
e = Entry(master)
e.pack()
e.delete(0, END)
e.insert(0, "")
Could you post a bit more code?