Related Clues:

• Make a noise on the way — and on the way back
• Horn's sound (T, not H)
• Palindromic honk
• Horn sound, in a children's book
• Use horn, going up and down
• Excessively tense, sound horn
• Blow in either direction
• Books going one way and another - blast!
• Sound horn up and down
• It's a driver's warning, anyway
• Sound one's horn
• Sort of sound that may be reflected without change
• Blow a horn
• Excessively tense to play the flute
• Car-horn beep