Sandbank (4)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sandbank</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for reef that I've seen before include "Rock formed of coral" , "Ridge near the surface of water" , "Rocky ridge near sea surface" , "marine hazard" , "Shorten sail" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sandbank</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that sandbank can be written as shoal)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for shoal that I've seen before include "Fish grouped" , "School of fish" , "Collection of fish" , "A great number of fish swimming together" , "Large group of fish - sandbank" .)