root = Tk()
frame = Frame(root, width=100, heigh=100, bd=11)
frame.pack()
label = Label(frame, text='Enter a digit that you guessed:').pack()
entry = Entry(frame, bd=4)
entry.pack()
entry.focus()
button1 = Button(root, width=4, height=1, text='ok')
button1.pack()
root.mainloop()
Setting focus to specific TKinter entry widget