recipe calls for 1 cup Corn Flakes crushed, is the 1 cup before or after crushing?

A few more thoughts.
If you're using the cornflakes in something like a breading mixture, it won't make much difference if you measure before or after crushing.
However, if you're using it in a recipe where you bake or cook, it might be better to use the lesser weight or volume (measure corn flakes whole, then crush).
That way, if you need to thicken the mixture you can always add some.
The reverse (using too much, then trying to re-balance the recipe) is harder.

Maybe it would help if we knew what the recipe is. I can see where interpreting it could go either way.

measure first, then crush. If it were to be crushed then measured, the wording would be "one cup crushed corn flakes"

If it states one cup crushed, it's after.

I don't know what the recipe is, but from the wording, it sounds as though first you crush the flakes, then pour them into a 1 cup dry measuring cup.