Singer went on about note being elevated (6)
I believe the answer is:
terfel
'singer' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'went on about note being elevated' is the wordplay.
'went' becomes 'left' (as in leaving).
'on' is an insertion indicator (as in clothing 'on' a person).
'about note' becomes 're' (as in do-re-mi. I am not sure about the 'about' bit.).
'being elevated' is a reversal indicator (in a down clue, letters go up).
'left' enclosing 're' is 'lefret'.
'lefret' reversed gives 'TERFEL'.
Can you help me to learn more?
(Other definitions for terfel that I've seen before include "Bryn --, opera singer" , "See 12" .)