Better blokes brought in by editor (5)
I believe the answer is:
emend
'better' is the definition.
(emending is a kind of bettering)
'blokes brought in by editor' is the wordplay.
'blokes' becomes 'men' (I've seen this in another clue).
'brought in by' means one lot of letters goes inside another.
'editor' becomes 'ed' (abbreviation).
'men' inserted into 'ed' is 'EMEND'.
(Other definitions for emend that I've seen before include "Improve (texts)" , "Remove faults from" , "change" , "Make improvements or corrections" , "make an improvement" .)