Preheat the oven to 180°C.
Butter or oil a deep oven-proof dish then lay the apple slices close together & on top of each other. Drizzle with the lemon juice, sprinkle with sugar &, cinnamon (and add the cloves & star anise if used).
Combine the flour with the cinnamon. Mix in the butter in small chunks and using your fingers and rub with the flour until you get a mixture resembling breadcrumbs. Add the sugar, mix well.
Sprinkle the crumble evenly on top of the apple, slightly pressing down.
Bake for about 30-35 minutes until golden.
Serve warm with custard, double cream or ice-cream.