Preheat oven to 350°.
Arrange apple in an 11 x 7-inch baking dish. Drizzle cider over apple.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, brown sugar, and cinnamon; cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal. Sprinkle flour mixture over apple mixture.
Roll dough into a 12 x 8-inch rectangle. Place dough over apple mixture; fold edges under, and flute. Cut 3 slits in top of dough to allow steam to escape.
Combine water and egg white, stirring well with a whisk. Brush dough with egg white mixture; sprinkle evenly with turbinado sugar. Bake at 350° for 40 minutes or until crust is golden brown.