Pressure, informally (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pressure informally</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for heat that I've seen before include "Cook" , "Energy that caues a rise in temperature" , "Warmth - gossip mag" , "Toast" , "early round" .)