Trader primarily supplying drinks on island (8)
I believe the answer is:
salesman
'trader' is the definition.
(thesaurus)
'primarily supplying drinks on island' is the wordplay.
'primarily' says to take the initial letters.
'drinks' becomes 'ales' (ale is a kind of drink).
'on' says to put letters next to each other.
'island' becomes 'man' (the Isle of Man is an example).
The initial letter of 'supplying' is 's'.
's'+'ales'+'man'='SALESMAN'
(Other definitions for salesman that I've seen before include "Death of a . . . . . . . . (Arthur Miller) (8)" , "One selling goods" , "''Death of a ...'' (drama by Arthur Miller)" , "Slam Sean badly for his selling" , "Male shop worker" .)