Possible Clues:

• Opposed to queen I backed in republic's capital
• Home to Strauss
• Austrian metropolis
• Site of Mozart's Figarohaus
• Compete with retired lady - that's capital!
• ''Amadeus'' setting
• Capital city on the Danube
• Capital city in which Queen turns up after six
• “This means nothing to me. Oh, ____” (Ultravox)
• After battle, Napoleon evacuated a part of Austria