Possible Clues:

• Refutation, contradiction
• Contradiction is about old Irish leader with gangster
• Victim in genuine denial
• Cask stuck in concrete is a contradiction
• Object of ridicule in genuine denial of charge
• Counter-statement
• Targeted person at centre of genuine counter-argument
• Argument against being genuine about joke's target
• Scapegoat in genuine denial
• Laughing stock snared by factual disproof