Possible Clues:

• Harsh pace, and not disheartened
• Singular weapon making loud noises
• Tumultuous southern river I had entered
• Rough walk starts with nettles and thorns
• Rough walk over Northern Territory
• Point spear for piercing
• The South gets 17 across to get sent about dirt back there
• Shrill and sharp enough at last for Neptune
• Urgent to make big move forward with books
• Small ballistic missile, shrill