Possible Clues:

• Composer Puccini
• -- Leopardi, 1798-1837, Italian poet
• Opera's Puccini
• Puccini's soldier — anarchist primarily, pacifist second
• Adventurer Casanova
• and 26 Across: A musician, I can go up to perform a turn with comic, foremost of impressionists
• Casanova's first name
• With 11 Down, a composer
• 2005 Kentucky Derby winner