Correct pieces penned by journalist (5)
I believe the answer is:
emend
'correct' is the definition.
(thesaurus)
'pieces penned by journalist' is the wordplay.
'pieces' becomes 'men' ('man' can be a synonym of 'piece').
'penned by' is an insertion indicator.
'journalist' becomes 'ed' (short for editor).
'men' inserted into 'ed' is 'EMEND'.
(Other definitions for emend that I've seen before include "Polish" , "Correct and improve the text" , "Correct, revise (text)" , "Remove errors" , "Improve by altering" .)