Related Clues:

• Sound on a track?
• "Ah, yes"
• Shrink's comment
• “Oh, now it’s clear”
• 'It's clear to me now'
• Half an iron-horse sound
• Syllable on a Valentine's Day card from Ralph Wiggum
• Chin-stroker's words
• 'Oh, so that's it'
• ''That's interesting''
• 'So that's how it is!'
• Nodder's comment
• 'Right, right'
• Statement of understanding
• 'Point taken'