In skillet cook bacon till crisp; drain, reserving 1/4 cup drippings in skillet. Set bacon aside. Cook onion and garlic in drippings until tender but NOT brown. Stir in butter till melted. Add clams and tuna; break tuna into chunks, along with bacon, olives,parsley, and pepper; heat through. Keep hot.
Meanwhile cook linguine according to package directions; drain. Place in warm serving bowl. At the table, top pasta with hot seafood mixture; toss. Serve with lemon wedges and grated parmesan cheese.