Cluttered (5)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cluttered</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for messy that I've seen before include "Disorganised" , "Untidy, dirty" , "Dirty and disorderly" .)