Possible Clues:

• 'Single maiden should go around clubs' is the wrong thing to say
• Grammatical (or social) blunder
• Only Conservative is above criticism, ultimately, for bad behaviour
• Ungrammatical use of words — breach of good manners
• Perhaps misuse of semicolons that's not on?
• Bit of nonstandard grammar
• Absurdity is only about doctrine
• Grammatical glitch
• Only one motorway, so going north's a mistake
• A mistake in the use of language