One editor has necessity (4)
I believe the answer is:
need
'necessity' is the definition.
('need' can be a synonym of 'necessity')
'one editor has' is the wordplay.
'has' indicates the answer is hidden within the clue.
'NEED' can be found hidden inside 'one editor'.
(Other definitions for need that I've seen before include "'miss'" , "Require (as essential)" , "Exigency" , "Want - poverty" , "Penury" .)