what is the tenors clef

I`m assuming you mean "What`s the tenor Saxes clef?" as this is a sax forum.

The tenor reads treble clef, but as it`s a transposing instrument (one octave and a tone below concert C) the music has to be transposed to sound correct. (the same with all saxes)

There is a "Tenor Clef" but this is very rarely used now.