Heard a note from a singer (5)
I believe the answer is:
tenor
'a singer' is the definition.
(I know that tenor is a type of singer)
'heard a note' is the wordplay.
'heard' shows a homophone (sound like).
'a note' becomes 'tenner' (ten pound note).
'tenner' sounds like 'TENOR'.
'from' acts as a link.
(Other definitions for tenor that I've seen before include "Drift of thought" , "Meaning - male singing voice" , "Pavarotti, for example" , "Eg, Placido Domingo" , "Singer (one of three?)" .)