Tissue sample test (6)
I believe the answer is:
biopsy
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tissue sample test</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 biopsy that I've seen before include "Test on living tissue" , "Microscopic test for disease" , "Test for infection" , "Examination of tissues to determine disease" , "Examination of tissues cut from living body" .)