Foreigner wanting more rum? (8)
I believe the answer is:
stranger
I believe this clue is a double definition.
'foreigner' is the first definition.
(I know that foreigner can be written as Stranger)
'more rum?' is the second definition.
(rum can mean strange)
'wanting' acts as a link.
(Other definitions for stranger that I've seen before include "One who is little known" , "More odd or unknown" , "Odder, more peculiar" , "Rent rags (anag)" , "The unknown one is more unusual" .)