Related Clues:

• Screwy enough to turn the big vessel over
• Screwy and round the bend
• A hard case in 23 across
• It's hard to be not all there
• The hard one might be a mad man
• You'd be mad to overturn the vessel like this
• This bally cracker sounds so sweet
• One of those with hard 20 across would be mad to turn the vessel over
• Litchi, e.g.
• It's hard to get a thread inside it
• Sounds as if the colonel is off his head in there
• The sap is off his head - a hard case
• Hard outside, thread inside
• Partner of 44 Across
• Macadamia, e.g