Thinking logically (9)
I believe the answer is:
reasoning
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">thinking logically</span>' is the definition.<br/ ><span class="explanation-format__explanation">('reason' can be a synonym of 'think logically')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for reasoning that I've seen before include "Thinking coherently and logically" , "Logic" , "Debating" , "sense?" , "argument" .)