Related Clues:

• You never go straight on board, sir
• You won't go straight on board, sir
• One can't go straight on board
• One won't go straight on board when it's dark at last
• One does not move straight on board, sir
• It's fair to say you sound dark, sir
• You're not to be taken lightly, sir, by the sound of it
• One does not go straight on board to help the mate
• 'Can't go straight on board, Sir (6)'
• Jumping chess piece
• Mail man?
• He's a Sir in the UK
• Audition of black horse
• Man said to be dark
• At end of dusk it's dark, man!