Related Clues:

• Taboo
• Still going
• Improper
• Forbidden by custom
• Contrary to good manners
• Unfinished
• It's unacceptable to be without a 26 down, it seems
• Half-baked, maybe
• Unacceptable to polite society
• Raw - and that's bad form
• Simply taboo
• Half-baked, say