Set forth (6)
I believe the answer is:
assert
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">set forth</span>' is the definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for assert that I've seen before include "Establish control or state as true" , "State authoritatively" , "State categorically" , "Affirm, allege" , "Contend, maintain" .)