witch-hunt

Short definition from Wiktionary

Noun

1. 1
   A search for people believed to be using sorcery or harmful magic, typically in order to persecute or punish them.
2. 2
   An attempt to find and punish or harass a group of people perceived as a threat, usually on ideological or political grounds.
3. 3
   A public or political campaign or investigation which smears a person or group.
4. 4
   Alternative form of witch-hunt.

Verb

1. 1
   To perform a witch-hunt.