Possible Clues:

• Imply complexity in old area that's plain in Greece
• Manet masterpiece
• London venue - Greek Games site
• Original setting for many events, it's plain
• Grecian plain, Zeus's chief sanctuary
• Old play I'm revising for ancient sports ground
• Place of ancient Greek games
• Capital of Washington state
• Plain old play I'm to put out
• In Ancient Greece, a religious sanctuary dedicated to Zeus