Virginal (6)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">virginal</span>' is the definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for chaste that I've seen before include "Cheats (anag.)" , "Untouched ..." , "Pure - virtuous" , "Refraining from sex" , "Decorous" .)