hired gun
noun[C]
USinformalukusanexpertwho isbroughtinto acompanyor anorganizationtodealwith aparticularproblemorsituation:
Boardmembersinstalledin themidstoftakeoverfightsarehiredgunswith aclearagenda.
apersonwho ispaidto do aparticularjob,especiallysomething thatothersmayconsiderto bemorallywrong:
Theyaccusedthe otherpartyof usinghiredgunstoturninfraudulentregistrationsthat theyplanto makesurearethrownout before theballotingstarts.