Possible Clues:

• Outsmart rep number one
• Literary hit
• Small square room for prisoners said to be consumed by drink? And that's supposed to be a success story!
• Successful book
• It flies off the shelves
• Book that tells us where to find the finest wines
• Very popular book or other product
• Hit top note, returning after time without piano
• Most successful rep gets a popular book
• What many people are buying? Trees to decorate with bells