Continuous dull pain (4)
I believe the answer is:
ache
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">continuous dull pain</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ache that I've seen before include "Throb - hurt" , "Persistent dull pain" , "Longing" , "Dull prolonged pain" , "Feel pain" .)