Possible Clues:

• Cheshire Cat specialty
• Put on a happy face, as hard work is cut short
• Beaming expression
• Show amusement as Romeo is caught in a trap
• Taking a drink round river brings a smile
• '''Shorting'' the Pound? That will bring a smile to one's face!
• Expose incisors, perhaps
• Cheshire cat's signature feature
• React to amusement
• Happy reaction