Bring a large pot of salted water to boil, then add pasta and cook until just under cooked (about a 1 minute short of al dente).
While the pasta cooks, over medium high heat, in large, deep sauté pan heat the butter and 3 tablespoons olive oil until hot but not smoking. Add garlic and sauté until just golden (about 30 seconds). Add the tomatoes and cook until they begin to breakdown.
Add wine, clam juice, lemon zest and all but a tablespoon of the parsley. Bring to a boil.
Add clams, lower the heat and simmer uncovered, just until clams open, 7 to 8 minutes or until all the clams are opened.
Reserve ½ cup cooking water, then drain the pasta and add to the pan. Simmer, tossing occasionally, until the pasta is just tender (about a minute). If the pasta starts getting a bit dry, add some of reserved cooking water.
Remove from heat and taste for seasoning. Season to taste. Add the remaining parsley, and drizzle with remaining olive oil, tossing to coat. Transfer to serving dish and serve immediately.