Cause to feel isolated (8)
I believe the answer is:
alienate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cause to feel isolated</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for alienate that I've seen before include "Cause a friend to become hostile" , "Make hostile, cause to become unfriendly" , "Estrange, disaffect" , "Lose support of" , "Distance" .)