Research treatise (6)
I believe the answer is:
thesis
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">research treatise</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for thesis that I've seen before include "Analytical essay written for university degree" , "Academic essay" , "Essay putting forward a particular view" , "Theme for an essay" , "Academic dissertation" .)