Possible Clues:

• Work for voice(s) and orchestra
• Composition for 16-Across
• Musical work as prison farewell
• Sacred music piece featuring voice(s) and orchestra
• Accountant keeping a set of books at work
• Bach's 'Coffee —'
• Preserve farewell musical setting
• Choral work vessel delivered on leaving?
• Short oratorio – some descant at all?
• Oratorio on a sacred theme