Most diminutive (7)
I believe the answer is:
tiniest
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">most diminutive</span>' is the definition.<br/ ><span class="explanation-format__explanation">('tiny' can be a synonym of 'diminutive')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for tiniest that I've seen before include "I sent it, being the smallest" , "Most small" .)