Legal addendum (5)
I believe the answer is:
rider
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">legal addendum</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 rider that I've seen before include "Condition added to a legal document" , "Motorcyclist" , "given little weight" , "Proviso in a legal document" , "Equestrian - clause" .)