Solidify, coalesce (3)
I believe the answer is:
gel
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">solidify</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">coalesce</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for gel that I've seen before include "Take form" , "Thicken" , "Substance to fix hair in place" , "stiffen" , "well-spoken deb?" .)