Afterwards, city heavyweight welcomes queen (5,2)
I believe the answer is:
later on
'afterwards' is the definition.
('later on' can be a synonym of 'afterwards')
'city heavyweight welcomes queen' is the wordplay.
'city' becomes 'la' (Los Angeles).
'heavyweight' becomes 'ton' (I've seen this before).
'welcomes' means one lot of letters goes inside another (in sense of 'invites in').
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'ton' enclosing 'er' is 'teron'.
'la'+'teron'='LATER ON'
(Other definitions for later on that I've seen before include "in the future" , "this evening?" , "At a subsequent time" , "'Subsequently, afterward (5,2)'" , "Afterwards" .)