More marshy (7)
I believe the answer is:
muddier
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">more marshy</span>' is the definition.<br/ ><span class="explanation-format__explanation">('muddy' can be a synonym of 'marshy')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for muddier that I've seen before include "More obscure" , "Less clear" , "More confused" .)