Possible Clues:

• ''Cast off'' antonym
• Secure at shore
• Othello, maybe
• 'The road was a ribbon of moonlight over the purple __': Noyes
• "The road was a ribbon of moonlight over the purple __": Noyes
• Secure, as a yacht
• Low river in high ground
• Tie up one of the conquerors of 23
• "The Hound of the Baskervilles" setting
• River following low ground covered with heath?