In a bowl, combine the grapes, pears, 2 tablespoons flour and extract until blended. Spoon into a lightly greased 8-in. square baking dish. In another bowl, combine brown sugar, salt, cinnamon, nutmeg and remaining flour; cut in butter until mixture resembles coarse crumbs. Stir in walnuts; sprinkle over fruit.
Bake at 375° for 30 minutes or until lightly browned.