Besmirched a dull poet perhaps (8)
I believe the answer is:
polluted
'besmirched' is the definition.
Both the answer and definition are adjectives. Maybe there's a link between them I don't understand?
'a dull poet perhaps' is the wordplay.
'perhaps' indicates an anagram.
'dull'+'poet'='dullpoet'
'dullpoet' with letters rearranged gives 'POLLUTED'.
Can you help me to learn more?
(Other definitions for polluted that I've seen before include "Defiled" , "infected" , "Made dirty in duel plot" , "Made dirty or impure, water or air" , "Made dirty or impure (8)" .)