Fatiguing; boring (8)
I believe the answer is:
tiresome
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">fatiguing</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">boring</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for tiresome that I've seen before include "Rather boring" , "Causing impatience" , "irritating" , "So metier may be boring (8)" , "Causing boredom" .)