Cardiologist's tool (5)
I believe the answer is:
stent
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cardiologist's tool</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 stent that I've seen before include "Device keeping blood vessel open" , "Tax in Scotland" .)