Flu symptom (5)
I believe the answer is:
fever
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">flu symptom</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 fever that I've seen before include "Elvis hit" , "Pyrexia" , "eg Malaria" , "Heat of disease or extreme excitement" , "1950s hit for 11" .)