Copying a short, sharp ringing sound (5)
I believe the answer is:
aping
'copying' is the definition.
('ape' can be a synonym of 'copy')
'a short sharp ringing sound' is the wordplay.
'a short' means to remove the last letter.
'sharp' becomes 'apt' (I've seen this in another clue).
'ringing sound' becomes 'ing' (I can't justify this - if you can you should give a lot more credence to this answer).
'apt' with its last letter taken off is 'ap'.
'ap'+'ing'='APING'
Can you help me to learn more?
(Other definitions for aping that I've seen before include "Mimicking like monkey" , "Taking off" , "Making copy of" , "Sending up" , "Trying to repeat" .)