Delta deposit (4)
I believe the answer is:
silt
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">delta deposit</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 silt that I've seen before include "Sediment deposited by water as in channel" , "Material deposited by a river" , "Sediment deposited by a river" , "Jamboree" , "Mud deposit in a river" .)