Great question, which I am often trying to solve.
For me, it starts with teaching our Horizontal Stack. I refer to the middle of the field as “workspace” and often say “We do work in the middle.” This terminology allows me to tell players “If you’re not doing work, you can’t be in the middle of the field.”
I also took to clarifying clear spaces recently. I explained that cutters who have made a cut in the middle of the field and are clearing have 3 options: near sideline, far sideilne, or deep. I requested they ask themselves where they are going, and decide quickly.
Finally, I have done both the Cutting Tree (also an exercise to show how hard running a player should be during the flow of offense) and basically a relay race that takes a player through a cut and clear.
I’m not 100% on the effectiveness. This is the least experienced college team I’ve coached so it is no surprise they are struggling with this. Tough to say if these tactics are really working or it is mostly just additional reps.