Pick up on (6)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pick up on</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 detect that I've seen before include "Find out - notice" , "Discover the presence of, as Sherlock would" , "Discover, discern" , "Notice, sense" , "Discover existence of" .)