Preheat grill to medium-high heat (350° to 400°). Combine first 3 ingredients, 1 tablespoon oil, and 1 tablespoon lemon juice in a small bowl. Let stand 15 minutes.
Sprinkle semolina flour evenly over a large, rimless baking sheet. Place pizza dough on baking sheet, and pat into a 14-inch circle.
Brush grill grates with oil, and slide pizza dough onto grates. Grill, covered with grill lid, 2 minutes or until grill marks appear. Slide baking sheet under dough on grill, and reduce heat to medium. Sprinkle dough evenly with mozzarella, leaving a 3/4-inch border. Top with clam mixture, Parmigiano-Reggiano, and bacon. Grill, covered with grill lid, 8 minutes or until cheese melts and crust is lightly browned.
Meanwhile, combine parsley, salt, and remaining 1/2 teaspoon each oil and lemon juice in a small bowl. Remove pizza from grill, and top with parsley mixture. Serve immediately.