Wash the foot with soap and water. Dab with a 50/50 solution of iodine and water. Blot dry with paper towels and apply some styptic powder or corn starch to the nail to promote clotting. If its not too bad and bleeding stops then put her back in the coop. If it takes a while to clot and looks like it will start easily then keep her separate on an old towel and pop her on the roost at night. That way the nail has a chance to clot up through the night before she walks around on it and gets it dirty again.