Systematic investigation to establish facts (8)
I believe the answer is:
research
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">systematic investigation to establish facts</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 research that I've seen before include "Investigation designed to expand knowledge" , "university job" , "scientific survey" , "Thoroughly investigate" , "What may make you a doctor" .)