Expression of relief (4)
I believe the answer is:
phew
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">expression of relief</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 phew that I've seen before include "Gosh, I'm sweltering!" , "Gosh, that's a relief!" , "Exclamation of relief" , "What a relief! It's hot!" , "Expression of relief" .)