Kind of clef (6)
I believe the answer is:
treble
'kind of clef' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for treble that I've seen before include "Hit in inner ring of dartboard" , "Chorister; multiply by three" , "High voice - large drink" , "winning series" , "large measure" .)