Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 10 inch round cake pan.
In a small bowl, mix the brown sugar, cinnamon, 1 tablespoon flour, and 1 tablespoon melted butter.
In a large bowl, mix the 2 cups flour, white sugar, baking powder, baking soda, and salt. In a separate bowl, mix the 1/2 cup melted butter, orange juice, orange zest, and eggs. Stir the melted butter mixture into the flour mixture until well blended. Transfer to the prepared cake pan. Sprinkle with the brown sugar mixture.
Bake 30 minutes in the preheated oven, or until a knife inserted in the center comes out clean.