Possible Clues:

• Depend on accepting copper's answer
• Use an SASE
• The answer is that one may depend on its being around the piano
• Come back about thin layer of wood
• Come back and gather a whopper, say
• Return to sender
• Get back
• The answer is to get your nose to the grindstone once more
• E-mail command
• The answer is to work on the job again, it seems