Headstrong
(Other definitions for obdurate that I've seen before include "Implacable" , "uncommonly tough" , "Stubborn, unpersuadable" , "Stubbornly resistant" , "Impervious to persuasion" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">headstrong</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that headstrong can be written as wilful)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for wilful that I've seen before include "Deliberate - unreasonably stubborn" , "Disposed to disobedience and opposition" , "Done deliberately, not an accident" , "Perverse" , "Deliberately disobedient" .)