Karaoke singer's device (4)
I believe the answer is:
mike
'karaoke singer's device' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mike that I've seen before include "-- Oldfield, musician" , "M; man's name" , "letter in code" , "T [Thespian] Reid" , "Man" .)