Difficult, tiresome (6)
I believe the answer is:
trying
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">difficult</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ >'<span class="explanation-format__original">tiresome</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(trying can mean annoying or tiresome)</span><br/ ><br/ ></span>
(Other definitions for trying that I've seen before include "Aggravating" , "Upsetting" , "Stressful" , "irksome" , "Taxing" .)