Possible Clues:

• What the ballet dancer wore for the archbishop
• Detail often drawn by Degas
• Item in a Degas work
• Dainty attire
• Archbishop calling for union repeatedly
• "Swan Lake" getup
• Dancer's dress
• Archbishop Desmond in skirt?
• Express disapproval over usherette's top and skirt
• By the sound of it, excessively short skirt