Tweet greeting bishop in competition (7)
I believe the answer is:
chirrup
'tweet' is the definition.
(thesaurus)
'greeting bishop in competition' is the wordplay.
'greeting' becomes 'hi' (hi is a kind of greeting).
'bishop' becomes 'rr' (abbreviation for Right Reverend).
'in' indicates putting letters inside.
'competition' becomes 'cup' (I've seen this before).
'hi'+'rr'='hirr'
'hirr' going inside 'cup' is 'CHIRRUP'.
(Other definitions for chirrup that I've seen before include "Make series of notes like grasshopper" , "Tweet" , "Chirp" , "Sound made by a bird" , "Bird's sound" .)