tenderloin

Short definition from Wiktionary

Noun

1. 1
   The tenderest part of a loin of meat, especially of pork or beef.
2. 2
   A district of a city where corruption is common, often because the district is devoted to questionable businesses (peep shows, etc) which are easy for police to blackmail and extort.

Proper noun

1. 1
   A neighborhood of varying extent in midtown Manhattan, New York known for illicit entertainment and associated police corruption.
2. 2
   A similar neighborhood in San Francisco, California.
3. 3
   A similar neighborhood in Seattle, Washington.