The term PART OF D.E.A. can be solved by the four-letter word DRUG. The DRUG Enforcement Administration (DEA) is a federal law enforcement agency of the United States Department of Justice that is responsible for enforcing the Controlled Substances Act, which regulates the manufacture, importation, possession, use, and distribution of certain substances. The DEA works to reduce the availability of illicit drugs on the streets and to disrupt and dismantle DRUG trafficking organizations.