Possible Clues:

• Places to broadcast mass medium production
• Substance believed to emanate from mediums
• A medium sort of spirit
• Supposed the matter could be finding place most untidy
• Medium's output almost complete, as arranged
• Mediums extruded it
• Place most able to produce psychic phenomenon
• Nebulous aura - but can it be caught to sample?
• What you see in place most spooky?
• Medium substance, though maximum in camels, perhaps