The term BEST REPLACEMENT refers to the Beatles' replacement of their original drummer, Pete Best, with Ringo Starr in 1962. The crossword solutions for this term are STARR (5 letters), RINGO (5 letters), and SUB (3 letters). STARR and RINGO refer to Ringo Starr, who was chosen as the replacement for Pete Best. SUB is a shortened form of substitute, which is what Ringo Starr was when he joined the Beatles.