Ceremonious (6)
I believe the answer is:
formal
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ceremonious</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 formal that I've seen before include "stuffy" , "Conforming to standards of correctness" , "Punctilious" , "Official; stiff" , "Conforming to accepted rules, as of dress" .)