Strongman - he's smuggling riches from the south (8)
I believe the answer is:
hercules
'strongman' is the definition.
'he's smuggling riches from the south' is the wordplay.
'smuggling' is an insertion indicator (some letters smuggled inside).
'riches' becomes 'lucre' (I've seen this before).
'from the south' says the letters should be written backwards (in a down clue, letters go up).
'lucre' written backwards gives 'ercul'.
'hes' placed around 'ercul' is 'HERCULES'.
(Other definitions for hercules that I've seen before include "Strong man of mythology" , "Strong hero" , "One who laboured" , "His labours are legendary" , "In Greek myth, a hero noted for great strength and 12 labours" .)