A wading bird deflects sound (9)
I believe the answer is:
turnstone
'a wading bird' is the definition.
(turnstone is a kind of wading bird)
'deflects sound' is the wordplay.
'deflects' becomes 'turns' (I can't justify this - if you can you should believe this answer much more).
'sound' becomes 'tone' (tone is a kind of sound).
'turns'+'tone'='TURNSTONE'
Can you help me to learn more?
(Other definitions for turnstone that I've seen before include "Shore bird" , "Wader" , "Relative of sandpiper, named for how it seeks food" , "Small short-billed sandpiper" , "Sort of sandpiper" .)