The term CLEF OR DRUM can be solved by the crossword solution BASS, which is a four letter word. BASS is a type of musical instrument that is used to provide a low-pitched sound in an ensemble. It is usually played with the fingers or a pick and is used in many genres of music, including jazz, rock, and classical. The BASS is also used to provide a rhythmic foundation for other instruments. In some cases, the BASS can also be used to provide melodic lines.