Divide into three equal parts (7)
I believe the answer is:
trisect
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">divide into three equal parts</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 trisect that I've seen before include "breakaway group after sound test" , "cut into thirds" , "Cut into three parts" , "Divide into three equal parts" , "Cut into three pieces" .)