Better people brought in by editor (5)
I believe the answer is:
emend
'better' is the definition.
(emending is a kind of bettering)
'people brought in by editor' is the wordplay.
'people' becomes 'men' (men are people).
'brought in by' indicates putting letters inside.
'editor' becomes 'ed' (abbreviation).
'men' put into 'ed' is 'EMEND'.
(Other definitions for emend that I've seen before include "Rectify" , "Make improvements to (text)" , "Modify" , "Revise (a text) (E, not A)" , "Edit, improve" .)