Libretto
I believe the answer is:
book
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">libretto</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for book that I've seen before include "an item from the library" , "Hardback, say" , "Written work; reserve" , "Reserve - bets taken on a race" , "Reserve - publication" .)