Refuses to buy in protest (8)
I believe the answer is:
boycotts
(Other definitions for boycotts that I've seen before include "Sends to Coventry, won't do business with" , "Refuses to have anything to do with, ostracises" , "Refuses to have anything to do with, perhaps in business (8)" , "Refuses to have anything to do with, perhaps in trade" , "Refuses to trade with or recognise" .)