Spock's forte (5)
I believe the answer is:
logic
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">spock's forte</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 logic that I've seen before include "Sound reasoning" , "using premises" , "Rational thinking" , "this makes sense" , "Chain of reasoning" .)