Swear, assert (4)
I believe the answer is:
aver
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">swear</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">assert</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for aver that I've seen before include "Maintain - assert - allege" , "State; say" , "make a statement" , "Say firmly, declare" , "'Affirm, assert (4)'" .)