Actually, I'd be more concerned about how that maroon is going to tolerate the clarkki clownfish when it gets bigger. You may have a blood bath on your hands. Maroons don't tolerate other clowns in their tanks well when they get big. Of course, there are exceptions, but it's not the norm in my understanding.
Still, I remember feeling similarly when I set up my first saltwater tank! I was so careful placing the rock and decorations in my tank to make them look perfect to my liking, and when any fish dared to disrupt my arrangements, I had to fix their mischief right away. I came to understand overtime that fish getting comfortable in their surroundings WILL rearrange. In the same way that I move my couch, TV, and table and chairs in my rooms to best suite my needs, your fish will rearrange to best suite their needs. IMO, the behavior is a sign of a happy fish. It's just doing what comes naturally...cleaning and setting up house. LOL
With that said, you have several options.
You can let your fish enjoy its new digs by arranging things the way he/she wants to and live with the changes
You can keep putting the sand back every day and probably tick off the clown enough that it moves from that preferred hosting site to another site in the tank with less interference from its human caretaker.
You can add more sand to the tank (at least in that area) and see if that solves the issue
You can rearrange the tank a bit and move something large to that area and force the clown to pic a new hosting site.
Good luck with the new fish and its housekeeping activities.