Related Clues:

• Obeyed a flasher
• Lost momentum
• Hit the brakes
• Decelerated
• Went from 60 to 40, e.g.
• Applied the brakes
• Lost speed
• Put on the brakes
• Was not so fast as 9 across, perhaps
• Unfastened?
• Lost steam
• Impeded
• Tapped the brakes
• Went from 50 to 40
• Went from adagio to largo, say