Sick feeling (6)
I believe the answer is:
nausea
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sick feeling</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 nausea that I've seen before include "Feeling of revulsion" , "Aversion" , "Queasy feeling" , "Feeling of imminent sickness, may be caused by sea" , "Seasickness" .)