Usyk isn't going to just let him clinch. Athletically he doesn't have the foot speed or agility to match Usyk nor does he have the ring cutting to corner him. It's going to be very difficult for Fury to even get to him because Usyk is quick, highly mobile, and slippery. The big lugs that Fury previously fought stood right in front of him. They made it real easy for him to impose his size and physicality.
When Fury does push forward he'll also have to worry about getting caught with sharp counters on the way in. Usyk's straight left hand in particular. Unlike Fury's previous opponents Usyk can actually fight off the back foot. He can fight off the front foot, too.