Swollen gut? I'd fancy that's about right (6)
I believe the answer is:
turgid
'swollen' is the definition.
(thesaurus)
'gut? i'd fancy that's about right' is the wordplay.
'fancy' indicates anagramming the letters.
'that's about' means one lot of letters goes inside another.
'right' becomes 'r' (common abbreviation).
'gut'+'id'='gutid'
'gutid' with letters rearranged gives 'tugid'.
'tugid' going around 'r' is 'TURGID'.
(Other definitions for turgid that I've seen before include "(Of language) tediously pompous" , "Swollen; bombastic" , "Swollen; pompous (language)" , "'Pompous, inflated (6)'" , "Pompous (language); distended" .)