Prepare gnocchi according to package directions, omitting salt.
While the gnocchi are cooking, heat oil in a large nonstick skillet over medium heat. Add onion and garlic; cook 5 minutes or until soft, stirring frequently. Stir in tomatoes and clams. Bring to a boil; reduce heat, and simmer 10 minutes or until thick. Stir basil into sauce; cook 30 seconds. Serve over the gnocchi.