Playing well, with all the right notes (2,4)
I believe the answer is:
on song
'right notes' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'playing well with all' is the wordplay.
'playing' becomes 'on' (on can mean playing or performing).
'well' becomes 'so' (both can mean extremely).
'with all' becomes 'ng' (I can't justify this - if you can you should believe this answer much more).
'on'+'so'+'ng'='ON SONG'
'the' acts as a link.
Can you help me to learn more?
(Other definitions for on song that I've seen before include "In superlative form" , "Vocally" , "Performing well - in form (slang)" , "in fine form" , "Performing well (informal)" .)