Foreigners, as around the Nile, possibly (6)
I believe the answer is:
aliens
'foreigners' is the definition.
('alien' can be a synonym of 'foreigner')
'as around the nile possibly' is the wordplay.
'around' indicates putting letters inside.
'possibly' indicates anagramming the letters.
'nile' with letters rearranged gives 'lien'.
'as' going around 'lien' is 'ALIENS'.
(Other definitions for aliens that I've seen before include "Foreigners or extraterrestrials" , "Creatures from another planet" , "Science-fiction creatures" , "Beings from another planet" , "'Little green men'?" .)