Editor recruits staff to do what he does (5)
I believe the answer is:
emend
'do what he does' is the definition.
The definition suggests a singular noun but the answer is not.
'editor recruits staff' is the wordplay.
'editor' becomes 'ed'.
'recruits' indicates putting letters inside.
'staff' becomes 'men' (I've seen this in other clues).
'ed' going around 'men' is 'EMEND'.
'to' is the link.
(Other definitions for emend that I've seen before include "change" , "Alter to improve (text)" , "Polish" , "Edit, improve" , "make an improvement" .)