In a heavy 10-12 inch skillet, heat the olive oil until a light haze forms over it. Stir in the garlic and cook over moderate heat, stirring constantly, for about 30 seconds.
Pour in the clam broth and wine and boil briskly over high heat until the foam disappears and the liquid has reduced to about 3/4 cup. Remove from heat and set aside.
In a large kettle or soup pot bring the water and salt to a bubbling boil over high heat.
Drop in the spaghetti and stir it gently with a wooden fork or spoon for a few moments to prevent the strands from sticking to one another or the bottom of the pot.
Boil over high heat, for 7-12 minutes, or until the pasta is tender.
Test it by tasting a strand; it should be soft but al dente-that is, slightly resistant to the bite. Immediately drain the spaghetti into a large colander, lifting the strands with a fork to be sure it is thoroughly drained.
Transfer the spaghetti to a large heated serving bowl and toss it with the soft butter. Bring the sauce in the skillet to a boil over high heat and add the clams.
Cook the clams, turning them constantly, for 1 or 2 minutes. Then pour the clams and sauce over the spaghetti, sprinkle with parsley, and toss together with two large forks until all the ingredients are well mixed.
Taste and season with salt and white pepper. Serve at once.