Experts writing, by the sound of it (4)
I believe the answer is:
pros
'experts' is the definition.
(professionals)
'writing by the sound of it' is the wordplay.
'writing' becomes 'prose' (I've seen this in another clue).
'by the sound of it' shows a homophone (sound like).
'prose' is a homophone of 'PROS'.
(Other definitions for pros that I've seen before include "Opposites of cons" , "Positive arguments" , "Persons with knowledge and skill" , "Yes votes" , "Arguments in favour" .)