Trying (7)
I believe the answer is:
testing
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">trying</span>' is the definition.<br/ ><span class="explanation-format__explanation">('test' can be a synonym of 'try')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for testing that I've seen before include "Trying out" , "tiresome" , "of a difficult nature" , "Subjecting to 15 ac" , "Examining" .)