Soon, one gets ahead (4)
I believe the answer is:
anon
'soon' is the definition.
(synonyms)
'one gets ahead' is the wordplay.
'one' becomes 'an' (an apple is one apple).
'gets' says to put letters next to each other.
'ahead' becomes 'on' (synonyms).
'an'+'on'='ANON'
(Other definitions for anon that I've seen before include "Of unknown name (abbr)" , "Without known author" , "Nameless - presently" , "Shortly; unknown" , "Soon, shortly (archaic)" .)