The shoulder clod is part of the chuck primal, the chuck primal being the entire shoulder, upper foreleg, part of the neck, and first several ribs. They generally run 15-20 lbs. If you remove the clod from the primal, plus a few other pieces, what remains is the chuck roll, an equally large hunk of chuck. Clods can be cooked like rolls. You'll find an approach for chuck roll that Chris posted in the beef section under the Cooking tab above, or by searching 'chuck roll' in the Find tab.