Go soft (4)
I believe the answer is:
melt
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">go soft</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for melt that I've seen before include "Thaw" , "Liquefy; become tender" , "Calm" , "Become liquid by heating" , "Turn to liquid" .)