Unearthly life forms (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
aliens
(Other definitions for aliens that I've seen before include "Extra-terrestrial beings" , "Foreigners or extraterrestrials" , "Foreigners or creatures from outer space" , "Beings from another planet" , "Life-forms assumed to exist beyond Earth" .)