This cooks up really fast, and uses groceries that you can keep on hand.

2 teaspoons olive oil
2 garlic cloves, minced
2 tablespoons tomato paste
1 (8 ounce) bottle clam juice
2 (6 1/2 ounces) cans chopped clams, 1/2 cup juice reserved
(Dry white wine)
1 pound linguine or spaghetti
2 tablespoons chopped fresh parsley
1/8 teaspoon crushed red pepper flakes
1/4 teaspoon black pepper
1/3 cup Parmesan cheese

Bring a large pot of water to a boil over high heat. Meanwhile, in a large nonstick skillet, warm the oil over medium heat. Add the garlic and sauté for 1 minute. Stir in the tomato paste and cook, stirring constantly, until slightly thickened, about 10 minutes. While the sauce simmers, cook the pasta in the boiling water until al dente. Drain and return to the pot. Add the clams, parsley, red pepper flakes, and pepper to the skillet and heat through. Pour the mixture over the pasta and toss well to combine. Serve with the Parmesan cheese on the side, if desired.

I think you could make a pretty decent white clam sauce by leaving out the tomato paste.