Possible Clues:

• Mean knight would split one and tenpence once
• Finally, he goes for plan
• Mean to call it a day after international
• Joint endeavour's revealing plan
• What a mean thing to do!
• It's mean to have X in the din
• What a mean thing to think
• What a mean way to think!
• Mean to get the net up in the confused din
• Design that�s fashionable � tuppence short of a shilling