Shortly, soon (4)
I believe the answer is:
anon
I believe this clue is a double definition.
'shortly' is the first definition.
(synonyms)
'soon' is the second definition.
(synonyms)
(Other definitions for anon that I've seen before include "Nameless (abbr.); soon" , "Of unknown name (abbr)" , "Soon, shortly (archaic)" , "Soon, in a little while" , "coming after a call" .)