Foreign article containing porky? (5)
I believe the answer is:
alien
'foreign' is the definition.
(synonyms)
'article containing porky?' is the wordplay.
'article' becomes 'an' (indefinite article).
'containing' means one lot of letters goes inside another.
'porky?' becomes 'lie' (I've seen this in other clues).
'an' enclosing 'lie' is 'ALIEN'.
(Other definitions for alien that I've seen before include "Foreign, strange" , "Being from another world" , "Creature from another planet" , "Foreign (from outer space?)" , "repugnant" .)