Parrot's speech organ, essentially (4)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
echo
'parrot's' is the definition.
(thesaurus)
'speech organ essentially' is the wordplay.
'essentially' says the answer is hidden in the clue (essence can mean the inside of something).
'ECHO' can be found hidden inside 'speech organ'.
(Other definitions for echo that I've seen before include "repetitive" , "Nymph; E (radio comms.)" , "A natural sound reflection" , "Trace call" , "Response" .)