Gravelly glacial ridge (5)
I believe the answer is:
esker
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">gravelly glacial ridge</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for esker that I've seen before include "Gravel ridge; reeks (anag.)" , "Glacial ridge" , "bar, perhaps" , "gravelly deposit" , "Sediment" .)