Duck's instrument in "Peter and the Wolf" (4)
I believe the answer is:
oboe
'duck's instrument 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 "bit of wind" , "Walk with exaggerated movements" , "Reed instrument" , "Player" , "Orchestral piece" .)