Preheat oven to 425°F. Line a 10-inch tart pan with prepared pastry. Trim edges; set aside.
In medium bowl, combine sugar, pecans, flour, lemon juice, cinnamon and nutmeg. Add apples; toss well. Arrange in pastry-lined pan.
In small bowl, mix brown sugar, flour, butter, pecans and cinnamon with a pastry blender or fingertips until mixture resembles coarse meal. Spoon topping over apples.
Bake for 10 minutes. Reduce heat to 350°F; bake an additional 35 minutes. Cool on rack.