Goes back on (7)
I believe the answer is:
reneges
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">goes back on</span>' is the definition.<br/ ><span class="explanation-format__explanation">('renege' can be a synonym of 'go back on')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for reneges that I've seen before include "Goes back" , "Fails to fulfil a promise or obligation" .)