Become less (8)
I believe the answer is:
decrease
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">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 "cut back" , "Plummet" , "Go down" , "Contract" , "Decline" .)