Soak the raisins for 30 to 60 minutes. Separately crush the walnuts and mix with the zest, the cinnamon and the clove. Beat together the oil, sugar and eggs. Add the grated zucchini, raisins, walnuts, flour, mixed with the baking powder, soda and salt. Stir all the ingredients well. Pour the mixture into a buttered baking pan.