In a large bowl, combine plums and 3 tablespoons brown sugar. Combine 2 teaspoons flour, pepper, nutmeg and cloves; sprinkle over plums and toss to coat. Transfer to a greased shallow 1-qt. baking dish.
In a small bowl, combine oats with remaining brown sugar and flour. Stir in butter and orange zest until crumbly. Sprinkle over plum mixture.
Bake at 375° for 20-25 minutes or until topping is golden brown and plums are tender. Serve warm.