The term 'SHAWM SUCCESSOR' is a crossword solution that can be filled in with the four-letter word 'OBOE'. The OBOE is a woodwind instrument that is a member of the double reed family. It is commonly used in orchestras and concert bands, and is known for its distinctive sound. The OBOE is often considered to be the successor of the shawm, an ancient double reed instrument that was popular in Europe during the Middle Ages.