Preheat oven to 350 degrees. Butter a 9-by-5-inch loaf pan, line bottom with parchment and butter paper.
Beat butter and sugar with an electric mixer until light and fluffy. Beat in egg. Stir baking soda into applesauce. Mix dry ingredients, then add to butter mixture in 3 additions, alternating with applesauce. Stir in raisins. Pour batter into pan and bake until top springs back when pressed, 50 minutes. Cool in pan on a wire rack for 10 minutes, then turn out onto rack.
Make glaze by mixing lemon juice and confectioners' sugar. Spoon glaze over cake.