Catastrophic; appalling (6)
I believe the answer is:
tragic
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">catastrophic</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">appalling</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(tragic can mean horrible or appalling)</span><br/ ><br/ ></span>
(Other definitions for tragic that I've seen before include "Greatly distressing" , "Dreadful" , "Unfortunate" , "Exceedingly sad" , "Calamitous, very sad" .)