Abide by (4)
I believe the answer is:
obey
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">abide by</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 obey that I've seen before include "Comply with (instructions)" , "Heed" , "Carry out (an order)" , "Be ruled by" , "Comply with orders" .)