Place pork and water to cover in a large skillet; cook 30 minutes over medium heat. Remove from heat; refrigerate 30 minutes or until fat congeals and rises to surface.
Remove 2 table spoons fat from water, and place in a small saucepan . Drain pork, and transfer to a lightly greased 9- inch pie plate. Season to taste with salt and pepper. Set aside.
Add flour , 1/2 teaspoon salt, and 1/4 teaspoon pepper to saucepan; cook over medium heat, stirring constantly. Remove from heat, and set aside.
Layer apples over pork in pie plate . Sprinkle with sugar, mace, and cloves; dot with butter. Pour gravy over top.
Roll pastry to 1/8-inch thickness on a lightly floured surface; place over pork mixture in pie plate. Trim edges; seal and flute. Cut slits in top of crust to allow steam to escape. Brush crust with egg white. Bake at 375° for 45 minutes or until golden brown.