Related Clues:

• Failure for 7-Down
• Bringing a bottle of water through security, e.g
• Eating peas with a knife, e.g
• Words to Nanette?
• Proscribed action
• Forbidden double negative?
• Launch cancellation
• It's doubly acceptable to reject what's far from acceptable
• Not possible, futile
• Impossible rhymes
• One can't access this number more than once
• Unacceptable thing
• Such an area is forbidden
• Something not acceptaable
• Movement for one knight in time becomes tabu