Scrub clams well under running cold water to remove sand and seaweed.
In a pot, bring 1 cup water to a boil. Add clams and return to boiling. Reduce heat to medium-low, cover, and cook for 6 to 8 minutes, or until shells open. Discard any that do not open. Transfer clams to a pot or bowl. Let broth stand until sand settles.
In a saucepan over medium heat, melt butter with olive oil. Add onions, garlic, oregano, red pepper flakes, and salt. Cook until onions are tender, stirring occasionally. Add parsley and wine, and cook for 2 minutes.
Discard top half-shell from each clam. Put clams in bottom shell on a serving plate.
Carefully, without disturbing sand on bottom of pot, ladle clam broth into onion mixture. Heat until hot. Pour over clams.