Investigation aids (5)
I believe the answer is:
leads
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">investigation aids</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 leads that I've seen before include "What Prime Minister does" , "Guides; wires" , "Directs" , "singers principally?" , "stars" .)