In a medium bowl, cream together the butter and brown sugar. Beat in the eggs and mashed banana. Sift together the flour, baking powder, baking soda, salt, cinnamon, and cloves; blend into the banana mixture. Stir in the nuts. Cover, and chill for at least 1 hour.
Preheat the oven to 375 degrees F (190 degrees C). Lightly grease cookie sheets. Drop dough by rounded teaspoons onto the prepared cookie sheets.
Bake for 8 to 10 minutes in the preheated oven, or until no imprint remains when touched. Cool on wire racks.