Soon, long ago (4)
I believe the answer is:
anon
'soon long ago' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for anon that I've seen before include "Soon - nobody knows me" , "Soon - unknown author (abbr)" , "Nameless (abbr.); soon" , "Soon or presently" , "Presently - or unknown" .)