Singer of only one sound note? (5)
I believe the answer is:
tenor
'singer of only one sound note?' is the definition.
'tenor' can be an answer for 'note?' (thesaurus). I am not sure about the 'singer of only one sound' bit.
'sound note?' is the wordplay.
'sound' indicates a 'sounds like' (homophone) clue.
'note?' becomes 'tenner' (a tenner is a 10 pound note).
'tenner' is a homophone of 'TENOR'.
Can you help me to learn more?
(Other definitions for tenor that I've seen before include "Male voice (one of three?)" , "direction" , "High voice - low bell" , "Eg, Caruso" , "character" .)