Thin mud (4)
(Other definitions for silt that I've seen before include "Slimy mud" , "Mud deposit in a river" , "Mud deposited in a river or lake" , "Sediment deposited by a river" , "Fine sediment (often deposited by water)" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">thin mud</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for slime that I've seen before include "Goo" , "Slippery mud; slug trail" , "Gunge" , "Nasty slippery stuff" , "Moist slippery stuff" .)