Dish covering penny whistle (4)
I believe the answer is:
pipe
'whistle' is the definition.
(I've seen this before)
'dish covering penny' is the wordplay.
'dish' becomes 'pie' (I've seen this before).
'covering' indicates putting letters inside.
'penny' becomes 'p'.
'pie' enclosing 'p' is 'PIPE'.
(Other definitions for pipe that I've seen before include "Tobacco is smoked in it" , "Means of conveying" , "two hogsheads of wine" , "Something in the organ loft" , "Tube for conveying gas or liquid" .)