Heat oven to 375°F. Place pie crust in 9-inch glass pie plate as directed on box for One-Crust Filled Pie.
In large bowl, mix powdered sugar, 1/3 cup flour and the cinnamon. Gently stir in peaches until coated. Spoon into crust-lined pie plate.
In medium bowl, mix 3/4 cup flour, the brown sugar and cinnamon. Cut in butter, using pastry blender (or fork or pulling 2 table knives through mixture in opposite directions), until mixture looks like coarse crumbs. Sprinkle evenly over filling.
Bake 40 to 45 minutes or until topping is golden brown. Cover edge of crust with foil after 15 or 20 minutes of baking to prevent excessive browning.