Related Clues:

• Way back in time
• When dinosaurs roamed
• In ancient times
• Way in the past
• In days of old
• Tale starter, perhaps
• A long time past
• A good while back
• Before any of us can remember, perhaps
• Not recently a lengthy green light
• Not, in short, an ancient green light
• In the past a green light takes ages
• Not a short start and not recently
• Not a short, light start and not recently
• 'Not, in short, 17 down (4,3)'