Comprehensive and thorough (2-5)
I believe the answer is:
in-depth
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">comprehensive and thorough</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for in-depth that I've seen before include "Full" , "Comprehensive and thorough" , "With thorough and extensive investigation" , "Thorough and intensive" , "Getting to the bottom of it" .)