Apple Crumble Pie

Purchased pie crust, an assortment of apples. As I prepared the apples, I dropped them into a bowl with orange and lemon juice. Then added brown sugar, a bit of white sugar, butter, cornstarch, cinnamon, cloves, nutmeg.
For the crumb topping, I put 1 cup flour, 1 stick butter, 2/3 cup brown sugar, 1/4 tsp. salt, and some walnuts I had left in a bag in the back of the cupboard.
Put filling into crust, top with crumb mixture, bake 400F for about 40-50 minutes.