Possible Clues:

• With 52-Across, John Lennon's mate
• John left Cynthia for her
• "Dear ___" (John Lennon song)
• Mother of Sean
• Video game composer Shimomura
• Conceptual artist Ono
• 'The Memory Police' author Ogawa
• 'Scattered All Over the Earth' author Tawada
• Ono who sang with John Lennon
• Artist and activist Ono