Exhalation of relief (4)
I believe the answer is:
sigh
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">exhalation of relief</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 sigh that I've seen before include "Exhale resignedly" , "resigned response" , "Exhale deeply" , "Exhale loudly" , "Exhalation of breath, with relief say" .)