Where lines of tenors may be seen (4,4)
I believe the answer is:
bass clef
'where lines of tenors may be seen' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
This is all the clue.
Can you help me to learn more?
(Other definitions for bass clef that I've seen before include "shower of pitch" , "Pitch symbol on stave (music)" , "Musical stave marking" , "Musical notation with F on the fourth line of the stave" .)