Section of a book (7)
I believe the answer is:
chapter
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">section of a book</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 chapter that I've seen before include "religious assembly" , "Ecclesiastical assembly or subdivision of a written work" , "Distinctive period of history" , "one section of book" , "Division of written work" .)