The acronym ANTI-DUI GRP stands for ANTI-Drunk Driving Group, and the four letter solution to the crossword is MADD, which stands for Mothers Against Drunk Driving. MADD is a non-profit organization that was founded in 1980 by a mother whose daughter was killed by a drunk driver. The organization works to raise awareness about the dangers of drunk driving and to advocate for stronger laws and penalties against drunk driving. They also provide support to victims of drunk driving and their families.