Say for sure (4)
I believe the answer is:
aver
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">say for sure</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 aver that I've seen before include "To declare or affirm solemnly as true" , "State firmly - even rave about" , "Say firmly, rave if necessary" , "being assertive" , "Maintain - state" .)