Insightfulness (6)
I believe the answer is:
acumen
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">insightfulness</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for acumen that I've seen before include "Keen insight, shrewdness" , "ability to make good judgements" , "Keen intelligence" , "Ability to take well judged decisions" , "'Shrewdness, in business perhaps (6)'" .)