Niftiest
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">niftiest</span>' is the definition.<br/ ><span class="explanation-format__explanation">('neat' can be a synonym of 'nifty')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for neatest that I've seen before include "Most tidy" , "Seat ten (anag)" , "Most orderly" , "Most smart" , "best-looking desk, say?" .)