Possible Clues:

• Vesuvius action
• An explosion as of volcano
• Volcanic outburst
• Volcanologist's study
• Not about one pure turn coming out here
• On the contrary, it gets to be pure outcome
• Rash which blighted Pompeii?
• Etna action
• No one perfect, including leader of Tories, on reflection, is rash
• Break out into dancing after perfect return