Mild or medium note (9)
I believe the answer is:
temperate
'mild' is the definition.
(similar in meaning)
'medium note' is the wordplay.
'medium' becomes 'tempera' (I've seen this before).
'note' becomes 'te' (musical note).
'tempera'+'te'='TEMPERATE'
'or' is the link.
(Other definitions for temperate that I've seen before include "benign" , "comfortably warm?" , "Controlled" , "even" , "Abstemious" .)