Diminish — curtail (7)
I believe the answer is:
abridge
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">diminish</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">curtail</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for abridge that I've seen before include "Abbreviate, shorten" , "Edit down" , "Shorten by using fewer words" , "Make a precis of" , "(US) cattle-pen" .)