Indefatigable (10)
There are a few possibilities for this:
persistent
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">indefatigable</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for tireless that I've seen before include "Full of energy" , "Never wearying" , "Having great energy" , "Indefatigable, unflagging" , "Full of stamina" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">indefatigable</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">indefatigable</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 persistent that I've seen before include "Tenacious; constant" , "Resolute - interminable" , "Not taking "no" for an answer" , "hanging on" , "not giving up" .)