Decompression sickness (3,5)
I believe the answer is:
the bends
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">decompression sickness</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for the bends that I've seen before include "on high mountain roads?" , "suffering when going under?" , "Sickness which drivers must watch out for" , "Decompression sickness; Radiohead album" , "A risk for divers" .)