Origin of clef
Examples from the Web for clef
They could only be written (as they are yet) in one clef—namely, the F clef.Shakespeare and Music|Edward W. Naylor
After a change of clef in the middle of a score this is, of course, not necessary.
It will be noted that in each case the line on which the clef is placed represents "middle C."Music Notation and Terminology|Karl W. Gehrkens
She was so tall the girls always considered her in that clef.The Girl Scouts at Rocky Ledge|Lilian Garis
This was what has since become the fourth line, the clef line, of the bass stave.