In saucepan combine one 6-ounce can tomato paste; 1/4 cup chopped onion; 1/4 cup chopped green pepper; 1 clove garlic, crushed; 1/2 to 3/4 teaspoon dried basil leaves, crushed; 1/2 tea spoon dried oregano leaves, crushed; 1/2 tea spoon salt; and 1/8 teaspoon pepper.
Blend in 1 cup water.
Drain two 7 1/2-ounce cans minced clams and one 3-ounce can sliced mushrooms, reserving liquids.
Add liquids to saucepan; set clams and mushrooms aside.
Simmer tomato mixture, uncovered, to desired thickness, about 45 to 50 minutes.
Cook 8 ounces spaghetti; drain.
Add clams and mushrooms to sauce; heat through.
Serve sauce over spaghetti.