Preheat oven to 180 degrees C. Grease and lightly flour a medium cake tin and set aside.
Filling: Combine the apple wedges with water and sugar in a saucepan over medium heat and bring to the boil. Reduce the heat and simmer for 10 minutes or until the apples are tender, but not overcooked. Remove from the heat and set aside.
Crumble: Into a mixing bowl, combine the flour, oats, sugar and cubed butter and mix with your hands until it resembles crumbs.
Spoon half of the crumble mixture into the base of the prepared cake tin and press down with the back of a spoon, sprinkle a little up against the sides.
Bake in the oven for 10 minutes until starting to turn golden brown. Remove from the oven and spoon apple mixture over crumble case, and sprinkle with raisins and cinnamon. Cover with the rest of the crumble.
Bake in the oven for another 20 to 25 minutes, or until golden brown. Remove from the oven and serve warm.