Retch (5)
I believe the answer is:
heave
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">retch</span>' is the definition.<br/ ><span class="explanation-format__explanation">(heaving is a kind of retching)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for heave that I've seen before include "Haul - retch" , "Lift or throw with great effort" , "Retch - lift using much effort" , "Pull hard; (sea) swell" , "Pull - retch" .)