Pot roughly round, roughly litre content (8)
I believe the answer is:
cauldron
'pot' is the definition.
(I know that cauldron is a type of pot)
'roughly round roughly litre content' is the wordplay.
'roughly' becomes 'ca' (abbreviation for circa).
'roughly' indicates an anagram.
'litre' becomes 'L' (abbreviation).
'content' means one lot of letters goes inside another.
'round' with letters rearranged gives 'udron'.
'udron' placed around 'l' is 'uldron'.
'ca'+'uldron'='CAULDRON'
(Other definitions for cauldron that I've seen before include "Place that's seething" , "Witches' pot" , "A large deep pot for boiling things" , "Large cooking pot" , "Witch's brewing pot" .)