Possibly cures an affliction (5)
I believe the answer is:
curse
'an affliction' is the definition.
(curse is a kind of affliction)
'possibly cures' is the wordplay.
'possibly' indicates anagramming the letters.
'cures' with letters rearranged gives 'CURSE'.
(Other definitions for curse that I've seen before include "Excommunication" , "Wish harm on" , "Utter obscenities" , "Cuss" , "Evil spell - oath" .)