A symbol placed at the beginning of the staff to denote which notes are indicated by the lines and spaces. The most common clefs are:the bass, or F clef, which is indicated by a stylized F, and encompasses the tones of G - a-sharp;the treble, or G clef, indicated by a stylized G, and encompassing the tones of e 1 - f-sharp 2;the movable, or C clef, indicated by a symbol which points to any of the five lines of the staff, indicating that that line is the pitch middle C or c 1.the symbol used at the beginning of a staff to indicate which lines and spaces represent which notes. in modern practice, only three clefs are commonly used, the 'g clef' or treble clef, the 'f clef' or bass clef, and the 'c clef', when used as an alto clef.