Possible Clues:

• Otherwise, in music
• Oasis reforming for musicians, or...
• Return of opera is sound, giving an alternative in music
• Easier version, in music scores
• Musical term for an alternative passage which may be played instead of the original passage
• Easier version indicator, in music scores
• Alternative passage in music
• Musical alternative in loss Iago suffered
• Or, in a musical score
• Direction to an alternative musical passage