Conclude by reasoning (5)
I believe the answer is:
infer
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">conclude by reasoning</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 infer that I've seen before include "Deduce (from evidence)" , "Conclude or judge from facts" , "Derive as a consequence" , "come to a conclusion" , "Deduce by reasoning" .)