The term 'Carson Forerunner' is a reference to the American television host and comedian Johnny Carson, who was a forerunner in the late-night talk show genre. The crossword solution for this term is PAAR, which stands for Paul Anthony Anderson Reiser, an American stand-up comedian, actor, author, and musician. Reiser was a frequent guest on The Tonight Show Starring Johnny Carson, and is often credited with helping to popularize the late-night talk show format.