Pepys kept one (5)
I believe the answer is:
diary
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pepys kept one</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 diary that I've seen before include "Daily record of personal activity" , "Pepys's record" , "Appointment book" , "Personal record book" , "Log of daily activity" .)