Honest round writer (4)
I believe the answer is:
open
'honest' is the definition.
('open' can be similar in meaning to 'honest')
'round writer' is the wordplay.
'round' becomes 'o' (round can mean a round object).
'writer' becomes 'pen' (I've seen this before).
'o'+'pen'='OPEN'
(Other definitions for open that I've seen before include "Golf tournament" , "Frank and unlocked" , "gaping" , "such a verdict?" , "hardly high-security" .)