In brief, soon (7)
I believe the answer is:
shortly
I believe this clue is a double definition.
'in brief' is the first definition.
(thesaurus)
'soon' is the second definition.
('shortly' can be a synonym of 'soon')
(Other definitions for shortly that I've seen before include "Soon: in an abbreviated manner" , "Soon; sharply" , "In a jiffy" .)