Possible Clues:

• Such as passes through Greenwich
• Great circle through the poles
• A girdle round the earth?
• Peak in clear -- one near borders
• Read mini novel - the one dividing the Poles
• Admire in convertible passing thought the poles
• Longitude line
• The setter's clear on Botham perhaps -- the top!
• Notional circle passing through both poles
• Happening at noon