Instrument that represents the duck in "Peter and the Wolf" (4)
I believe the answer is:
oboe
'instrument that represents the duck in peter and the wolf' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for oboe that I've seen before include "Source of music" , "Reed instrument" , "Double-reeded woodwind instrument" , "Instrument used in 1d" , "Cor anglais in its family" .)