Lets up (6)
I believe the answer is:
abates
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lets up</span>' is the definition.<br/ ><span class="explanation-format__explanation">('abate' can be a synonym of 'let up')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for abates that I've seen before include "Becomes less intense" , "Slacks off" , "lowers" , "Calms down a" , "Grows less intense" .)