Unfamiliar, strange (5)
I believe the answer is:
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">unfamiliar</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">strange</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for alien that I've seen before include "One is from outer space, perhaps" , "extraneous" , "coming from overseas" , "Foreign - film directed by Ridley Scott" , "repugnant" .)