Related Clues:

• Exclamation akin to 17-Down
• "Surprise!"
• Cry of satisfaction
• ''Thought so!''
• Cry when a light goes on
• 'The penny drops!'
• Word of discovery
• I've got it!
• Sudden understanding
• Cry upon figuring out 66-Across
• It's "eureka!" either way
• 'Here's the answer at last!'
• Bingo alternative?
• "I finally get it!"
• Exclamation of knowledge