Declare firmly (6)
I believe the answer is:
insist
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">declare firmly</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for insist that I've seen before include "Continue to assert, maintain" , "Demand firmly" , "Declare or demand emphatically" , "Be firmly demanding" , "Refuse to give way" .)