Preheat oven to 425°.
Fit dough into a 9-inch pie plate. Fold edges under; flute.
Combine 1/3 cup brown sugar, flour, and cinnamon in a bowl. Sprinkle over peaches; toss gently. Spoon into crust.
Combine 1/3 cup brown sugar, oats, and butter; sprinkle over peach mixture. Bake at 425° for 10 minutes. Reduce oven temperature to 375°; shield edges of crust with foil, and bake an additional 25 minutes or until golden. Cool on a wire rack.