Heat oven to 375°F. Grease 12x8-inch (2-quart) baking dish. In large bowl, combine all fruit mixture ingredients; toss to coat. Spoon into greased baking dish.
In small bowl, combine rolled oats, brown sugar and 1/3 cup flour. With pastry blender or fork, cut in margarine until crumbly. Stir in nuts. Sprinkle topping evenly over fruit.
Bake at 375°F. for 30 to 40 minutes or until topping is golden brown and apples are tender. If desired, serve with ice cream, whipped cream or whipped topping.