Copying a high-pitched sound (5)
I believe the answer is:
aping
'copying' is the definition.
('ape' can be a synonym of 'copy')
'a high-pitched sound' is the wordplay.
I cannot quite see how this works, but
'a' is present in the answer.
'sound' could be 'ping' (pinging is a kind of sounding) and 'ping' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for aping that I've seen before include "Acting like a parrot" , "Imitation" , "Trying to repeat" , "Imitating, copying" , "Making copy of" .)