In the bowl of a food processor fitted with a metal blade, combine the flour, pecans, sugar, and salt until the pecans are finely chopped. Add the butter and pulse until crumbs start to form. Add the egg and pulse until the dough comes together. Chill for 20 minutes or until needed. Press 3/4 of the dough into a 9-inch pie plate, reserving the remainder for the crumble topping. Bake in a preheated 375° F oven until golden or according to your pie recipe instructions.