One’s piano tune better? Just the opposite (6)
I believe the answer is:
impair
'better? just the opposite' is the definition.
I can't tell whether this definition defines the answer.
'one's piano tune' is the wordplay.
'one's' becomes 'I'm' ('one is' is a formal way of saying 'I am').
'piano' becomes 'p' (musical abbreviation).
'tune' becomes 'air' (air can mean a piece of music).
'im'+'p'+'air'='IMPAIR'
Can you help me to learn more?
(Other definitions for impair that I've seen before include "Make worse or less effective" , "blunt" , "Spoil strength, quality of" , "Harm" , "Courteous man (colloq.)" .)