Possible Clues:

• Dreadfully saddened there can be no progress here
• Awful deeds and situations offering no way out
• Leads someone down the garden paths for final goals
• Dees! They go nowhere!
• Fruitless pursuits, and a feature of 14-, 19-, 32-, 39- and 47-Across
• They make you turn around or back up (2 words)
• They lead nowhere
• Eventually we'll all come to these streets
• They lead you nowhere
• Inside, theologians each study blind alleys