Hard to brush off (9)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hard to brush off</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for insistent that I've seen before include "Declaring or demanding emphatically" , "Demanding attention" , "Emphatic" , "Determined" , "Compelling attention" .)