Savage, unfeeling (6)
I believe the answer is:
brutal
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">savage</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">unfeeling</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for brutal that I've seen before include "Very cruel, merciless" , "Savagely violent" , "Cruel, heartless" , "extremely honest" , "Cruel and unfeeling like an animal" .)