Pertaining to the heart (7)
I believe the answer is:
cardiac
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pertaining to the heart</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 cardiac that I've seen before include "Physiologically, of the heart" , "Relating to the heart" , "Sort of surgery" , "Relating to 8 down, part one" , "of hearts" .)