Witch’s pot (8)
I believe the answer is:
cauldron
'witch's pot' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cauldron that I've seen before include "Witches' vessel" , "Witches' pot" , "Very large pot used for boiling" , "Large kettle" , "Place that's seething" .)