GLAD TAGS 
RE:
Solver's "undo" implement ERASER
I guess most Xwords are done on paper in pencil and with erasers, but there are some of us who use pen. (I do because it stands out better on newsprint.) I pride myself in filling out correctly a complete grid with no write-overs. But most of the time I can't, and today was no exception.
At 54-Down, clued by "Act like a couch potato," I had the first two letters, L and O, and wrote the obvious answer, LOAF. Wrong! It was LOLL, and now I have to wait another day for perfection.
Speaking of perfection, at my age and experience one would think there would be no words I would not know
on a Monday. Wrong again! Never heard of HIDEYHOLE.
