Sort of diet that is offensive (6)
I believe the answer is:
foetid
'offensive' is the definition.
Both the definition and answer are adjectives.
Perhaps there's an association between them I don't understand?
'sort of diet' is the wordplay.
'sort' is an anagram indicator.
'of'+'diet'='ofdiet'
'ofdiet' with letters rearranged gives 'FOETID'.
'that is' acts as a link.
Can you help me to learn more?
(Other definitions for foetid that I've seen before include "Smelling unpleasant" , "Foul-smelling" , "Evil-smelling" , "Smelly" , "rank" .)