Written study (8)
I believe the answer is:
treatise
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">written study</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for treatise that I've seen before include "Iterates in dissertation" , "Written work dealing with one subject" , "Learned written work" , "Formal written work dealing with a particular subject" , "Written exposition of an argument" .)