Ignored editor supporting past appearance (10)
I believe the answer is:
overlooked
'ignored' is the definition.
(I've seen this in another clue)
'editor supporting past appearance' is the wordplay.
'editor' becomes 'ed' (abbreviation).
'supporting' says to put letters next to each other (in a down clue, some letters go below others).
'past' becomes 'over' (I've seen this in other clues).
'appearance' becomes 'look' (look is a kind of appearance).
'over'+'look'='overlook'
'ed' after 'overlook' is 'OVERLOOKED'.
(Other definitions for overlooked that I've seen before include "Had in sight" , "missed" , "Neglected - visible from above" , "Failed to notice" , "allowed to go unpunished?" .)