Change from liquid to vapour (9)
I believe the answer is:
evaporate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">change from liquid to vapour</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 evaporate that I've seen before include "Turn liquid to gas" , "Melt away" , "go a stage further?" , "let off steam" , "Fade away gradually" .)