Possible Clues:

• See 4
• Stephen --, 1942-2018, English theoretical physicist
• Stephen --, author of 'A Brief History of Time'
• See 1
• "A Brief History of Time" author Stephen
• 'A Brief History of Time' author Stephen
• Physicist has May meeting with top man
• Stephen __, author of A Brief History of Time
• Peddling
• See 17 Across