I found those difficult, too. I think we are to read WASH as in "it's a wash" -- which is like a tied game, or a tie. And FELL as a verb means to knock down, or "level" something. Fun puzzle, BTW.
Thanks for the reply; I've never heard a tied game called a "wash" - perhaps it's another US v UK issue. I don't see how FELL is synonymous with "slid".