Guitar accessory (4)
I believe the answer is:
capo
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">guitar accessory</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for capo that I've seen before include "Gangster boss" , "crime boss" , "Head honcho in Cosa Nostra" , "something to grip neck tightly" , "Mafia chief?" .)