Artificially high voice (8)
I believe the answer is:
'artificially high voice' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for falsetto that I've seen before include "Unusually high voice" , "Extra high male singing voice" , "Forcedly high voice" , "High-pitched voice above natural range" , "Unnatural voice" .)