Mix apples, brown sugar, water and lemon juice in 2 qt saucepan. Heat to boiling; reduce heat. Cover and simmer just until apples are tender, 7-8 minutes.

Mix flour, sugar and salt; stir into apple mixture. Cook, stirring constantly, until mixture thickens. Stir in vanilla and butter until melted; cool.

Heat oven to 425 degrees. Prepare pastry. Turn apple mixture into pastry shell. Top with crumb topping.

Cover edge with 2 inch strip of aluminum foil to prevent excessive browning. Bake 40-45 minutes. Remove foil for last 15 minutes of cooking.