Botswana -- the magician comes with this imprecation (8)
I believe the answer is:
anathema
'this imprecation' is the definition.
'botswana the magician comes with' is the wordplay.
'with' indicates the answer is hidden within the clue.
'ANATHEMA' is hidden within 'botswana the magician comes'.
(Other definitions for anathema that I've seen before include "Accursed by the Church" , "Something hated" , "Curse - church ban" , "Formal church curse of excommunication" , "Something very greatly disliked" .)