Related Clues:

• Understandable by only an enlightened inner circle
• Mysterious to all but a chosen few
• Intelligible only to informed people in coteries
• Abstruse, arcane
• Intelligible only with special knowledge
• 'Abstruse, arcane (8)'
• Understood by only a few people
• It's a mystery how Eric can have got his toes broken
• For the initiated, it's broken toes the boy has
• Is 'e that secret drinker, Eric?
• It's difficult to understand how with broken toes he makes it
• It's mysterious how the boy can have got broken toes
• It's hard to believe that the boy is after having broken toes
• It's hard to understand how 'e, Eric, could be such a drunkard
• It's hard to understand how Eric gets his toes broken