Possible Clues:

• Nickname for a 63-Across 39-Down
• Musical premiere of 1805
• Symphony with a noted funeral march
• Musical work that Berlioz called 'a heavenly sweetness'
• 1805 Vienna premiere
• Vienna premiere of 1805
• Orchestral work premiered in 1805
• Name of Beethoven's third symphony
• … his third
• Symphony whose second movement is marked 'Marcia funebre. Adagio assai'