Cook linguine in lightly salted, boiling water for 8 to 10 minutes or until tender but still firm. Drain; keep warm.
Meanwhile, chop clams, reserving juice; set clams aside. Strain juice to remove bits of shell. (Or, drain canned clams, reserving the juice from 1 of the cans.) Add enough half-and-half, light cream, or milk to the reserved clam juices to equal 2 cups.
For sauce, in a medium saucepan cook onion and garlic in margarine or butter until tender but not brown. Stir in flour, oregano, salt, and pepper. Add half-and-half mixture all at once. Cook and stir until thickened and bubbly. Cook and stir for 1 minute more. Stir in clams, parsley, and wine. Heat through. Serve sauce over linguine. Sprinkle with Parmesan cheese.