Possible Clues:

• Elegant Windy City long since forgotten
• Smart little bird, not fully-fledged
• Suitable for a gala event
• "Good Times" band
• A la mode
• Fashionable good taste
• Elegance Caesar initiated here in ancient Rome
• In vogue for duplicate letters to include greeting
• How smart of the little bird to have shed its tail!
• Stylishness displayed by US city? Not in the past