Mix breadcrumbs and hazelnuts together. Prepare fish by dredging it in the flour, dipping it in the egg wash and coating the fillets with the breadcrumb/hazelnut mixture. Heat a heavy skillet over medium-high heat and fry the walleye fillets in clarified butter until the crust is a golden brown. Flip the fish and repeat on the other side. The flesh of the fish should be white all the way through, but not dry and flaky. Serve with lemon wedges for garnish.