Possible Clues:

• Creative idea
• Original idea of one employed in local office starts to influence local decisions
• After knock on the head, youngster gets wheeze
• Minerva's original idea?
• Product of creative thinking
• An original idea to mind the baby
• Someone's bright idea for a nail about 2.54 cm (one length)
• Bean product?
• Product of a fertile imagination?
• Youngster gets hit on the head before producing original work