Scrub clams thoroughly, discarding any that are cracked or open. Place remaining clams in a large bowl; cover with cold water, and sprinkle with cornmeal. Let stand 30 minutes. Drain and rinse clams, discarding cornmeal. Set clams aside.
Coat a medium nonstick skillet with cooking spray. Place over medium-high heat until hot. Add garlic, and saute 30 seconds. Add tomato and next 3 ingredients. Bring to a boil; reduce heat, and simmer, uncovered, 15 minutes, stirring occasionally.
Place clams on top of tomato mixture. Cover and cook 8 to 10 minutes or until clams open. Remove and discard any unopened clams.
Cook pasta according to package directions, omitting salt and fat. Drain. Remove clams from tomato mixture; set aside. Toss pasta with tomato mixture, and transfer to serving plates. Arrange clams evenly over pasta. Sprinkle with parsley.