Curiously reflect on musical character (5,4)
I believe the answer is:
tenor clef
'musical character' is the definition.
(symbol (character) in musical notation)
'curiously reflect on' is the wordplay.
'curiously' indicates anagramming the letters.
'reflect'+'on'='reflecton'
'reflecton' anagrammed gives 'TENOR-CLEF'.
(Other definitions for tenor clef that I've seen before include "One on the staff" , "instruction for a musician" , "It has middle C on second- highest line" , "A stave marking for pitch" , "Character instructing musician" .)