Soon, shortly (4)
I believe the answer is:
anon
This clue is a double definition.
'soon' is the first definition.
(synonyms)
'shortly' is the second definition.
(synonyms)
(Other definitions for anon that I've seen before include "before long" , "Writer unknown" , "Immediately" , "At another time and with no identity, in short" , "Soon, in a little while" .)