Possible Clues:

• 'Symphonie Fantastique' need
• The score for "Symphonie fantastique" has a part for it
• Neighbour coming round for instrument
• Neighbour's coming round - blow it!
• It's played by a blowhard
• Reviewed an objection to part of the brass section
• Oom-pah-pah-er
• ''Big'' band instrument
• Neighbour turns into a music-maker
• It has a solo near the end of 'An American in Paris'