Ringing instrument (4)
I believe the answer is:
bell
'ringing instrument' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for bell that I've seen before include "Tinkler" , "Scottish-born inventor of the telephone, d. 1922" , "End of oboe; inventor of telephone" , "inventive fellow" , "Boxing match signal" .)