Inhumane (5)
I believe the answer is:
cruel
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">inhumane</span>' is the definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for cruel that I've seen before include "Painful" , "Very unkind" , "Barbaric" , "Vicious" , "Sadistic, causing suffering" .)