Possible Clues:

• They cross in a crossword
• Puzzlebook section
• “They are useless. They can only give you ____” (Pablo Picasso, on computers)
• Comebacks? This side, they're going down!
• Meets requirements for an empty grid?
• Crib contents
• Acknowledges swans flying over English river
• Belgian port has succeeded for each end of port is satisfactory
• Rawness (anag)
• Trebek's reading