Kind of clarinet
I believe the answer is:
alto
'kind of clarinet' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for alto that I've seen before include "Singing range" , "The highest adult male singing-voice" , "Second of four parts (in singing)" , "Singer's hidden inside chemical toilet" , "Counter-tenor or contralto" .)