Stiff-necked (9)
I believe the answer is:
obstinate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">stiff-necked</span>' is the definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for obstinate that I've seen before include "Stubbornly persistent" , "Inflexible" , "Pig-headed" , "Mulish" , "Stubborn, obdurate" .)