Make or become less (8)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">make or become less</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 decrease that I've seen before include "Contract" , "Become smaller or fewer" , "Weaken" , "Reduce in size" , "Grow smaller or less" .)
(Other definitions for abate that I've seen before include "Lessen - cease" , "Ease off" , "(Flood) recede" , "Go down like storm" , "Die down, slacken off" .)