Niggle (4)
I believe the answer is:
fuss
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">niggle</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that niggle can be written as fuss)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for fuss that I've seen before include "Protest, complaint" , "Bustle and bother" , "To-do" , "Unnecessary agitation" , "Bustle; ado" .)