Possible Clues:

• Boring oldster is young after transformation
• Mephistopheles's task was extremely boring
• Monotonous style ruins good broadcast
• It's exasperating, old use maybe, having to sing about an ancient city
• It's very monotonous and said to be bad for one's shoes
• Unbearably monotonous, as lots of walking may be, one hears
• Tedious individual breaking down