Component of servo (Boeing instrument) (4)
I believe the answer is:
oboe
'instrument' is the definition.
(type of musical instrument)
'component of servo boeing' is the wordplay.
'component of' says the answer is hidden in the clue (I've seen this in other clues).
'OBOE' is hidden in the letters of 'servo boeing'.
(Other definitions for oboe that I've seen before include "Producer of notes" , "Double-reeded woodwind instrument" , "Instrument used in 1d" , "Woodwind instrument of treble pitch" , "Musical instrument" .)