Afterwards? Dead right! (5)
I believe the answer is:
later
'afterwards?' is the definition.
('later' can be a synonym of 'afterwards')
'dead right' is the wordplay.
'dead' becomes 'late' ('late' can be similar in meaning to 'dead'**).
'right' becomes 'r' (common abbreviation).
'late'+'r'='LATER'
(Other definitions for later that I've seen before include "bye" , "Subsequently" , "at a future date" , "Eventually" , "Tardier" .)