Dope having returned from Belfast? (4)
I believe the answer is:
info
'dope' is the definition.
(dope can informally mean information)
'returned from belfast?' is the wordplay.
'returned' is a reversal indicator.
'from' becomes 'of' (of can mean from or belonging to).
'belfast?' becomes 'NI' (Belfast is the capital of Northern Ireland).
'of'+'ni'='ofni'
'ofni' reversed gives 'INFO'.
'having' acts as a link.
(Other definitions for info that I've seen before include "Gen (colloq.)" , "Facts; knowledge gained" , "News" , "Facts (abbr)" , "Knowledge (colloq.)" .)