Alien working in forge (7)
I believe the answer is:
foreign
'alien' is the definition.
(I know that alien can be written as foreign)
'working in forge' is the wordplay.
'working' indicates anagramming the letters.
'in'+'forge'='inforge'
'inforge' is an anagram of 'FOREIGN'.
(Other definitions for foreign that I've seen before include "Exotic" , "Extraneous" , "not typical" , "Alien" , "Of or from another country" .)