Possible Clues:

• Understood by a few
• Turns up about to go to school in old transport - only those with specialised knowledge can get it
• Intended for a few
• Way out there
• Difficult to understand
• Intelligible only to the initiated
• Not widely known
• Recites novel about love - stuff that's puzzling to most
• Understandable only by an inner circle
• Drunk man goes to leading expert in private