Related Clues:

• Horn
• Warning sound
• Warning signal
• Warning horn
• Hooter
• Emergency horn
• Electric warning signal
• 'Ah-oooo-ga!' horn
• Plenty of horn?
• Loud warning signal
• Loud auto honker of yore
• Loud horn
• A kind of loud horn
• Might one not be so strict on the end of the old 30 across?
• One horn, not strictly on the end