Necessary; requisite (7)
I believe the answer is:
needful
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">necessary</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ >'<span class="explanation-format__original">requisite</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that requisite can be written as needful)</span><br/ ><br/ ></span>
(Other definitions for needful that I've seen before include "Nude elf (anag.)" , "poor" , "Required" , "Poverty-stricken" , "Indispensable" .)