Arrange rhubarb in a 9-inch greased casserole dish. Mix sugar, 1 tablespoon of flour and cinnamon and sprinkle over the rhubarb. Mix the 1 cup flour, baking powder and sugar together. Cut in the margarine using two knives or a pastry blender until mixture is crumbly. Combine the egg with milk and add to the dry mixture. Drop by spoon fulls over rhubarb mixture and spread. Bake at 350F for 25 minutes.