Painstakingly careful (8)
I believe the answer is:
thorough
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">painstakingly careful</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 thorough that I've seen before include "Attentive to detail" , "Attending to every detail - complete" , "Scrupulous in completing work" , "Painstakingly careful and accurate" , "Assiduous, painstaking" .)