Preheat oven to 325 degrees F (165 degrees C). Grease a 9x13-inch baking dish.
Combine carrots, raisins, water, sugar, orange juice, butter, cinnamon, cloves, and nutmeg in a small saucepan; bring to a boil. Reduce heat to low and simmer until slightly reduced, about 5 minutes. Pour carrot mixture into a large bowl and cool to lukewarm, 15 to 20 minutes.
Stir flour, egg, baking soda, and salt into carrot mixture until batter is well mixed; fold in walnuts. Pour batter into the prepared baking dish.
Bake in the preheated oven until a toothpick inserted in the center comes out clean, about 25 minutes.