Piece of water that is between the U.S. and Canada (4)
I believe the answer is:
erie
But I can't explain it at all! Could you help me understand?
(Other definitions for erie that I've seen before include "N. American lake" , "A Great American lake - sounds spooky" , "One of the Great Lakes" , "Spooky-sounding" , "North american lake sounds spooky" .)