Allowable (11)
I believe the answer is:
permissible
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">allowable</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that allowable can be written as permissible)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for permissible that I've seen before include "OK" , "Allowed" , "Allowable" .)