Most sacred (7)
I believe the answer is:
holiest
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">most sacred</span>' is the definition.<br/ ><span class="explanation-format__explanation">('holy' can be similar in meaning to 'sacred')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for holiest that I've seen before include "Most resembling sacred work" , "superlatively untouchable" , "Most pious" , "Most divine" , "most befitting to worship" .)