Accordionists, not content, disapprove over E sharp (6)
I believe the answer is:
astute
'sharp' is the definition.
(synonyms)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for astute that I've seen before include "Peerceptive" , "Able to make accurate assessments" , "'Perceptive, shrewd (6)'" , "Shrewd, wily" , "Wide" .)