Possible Clues:

• Roost
• Use the start of 17- or 50-Across or 11- or 25-Down?
• React to the music's stopping, perhaps
• What a cellist has to do before playing
• Be on one's rocker?
• Notwithstanding, have a little 24 across with it
• It's confused or it's backward, notwithstanding
• Watch a 37 Across
• Word to Rover
• Order to a canine