Hardy (6)
I believe the answer is:
robust
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hardy</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 robust that I've seen before include "Hardy and vigorous" , "Sturdy, resilient" , "Physically strong" , "Athletic" , "'Hearty, healthy (6)'" .)