Possible Clues:

• Crash of lone bus involving middle of bus? It's unclear
• Source of olive oil in America bathed in heat from the south? That's unclear
• Vague university fellow's knocked over, poor soul
• Cloudy and vague
• Cloudy and indistinct
• Vague and formless
• Indefinite, unclear
• Hazy, like a cloud
• Indistinct and vague
• Vague rule bosun amended without resistance