Fish; beam (3)
I believe the answer is:
ray
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">fish</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that ray is a type of fish)</span><br/ ><br/ >'<span class="explanation-format__original">beam</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for ray that I've seen before include "Beam of light or flat fish" , "A bright beam or flat fish" , "may be electric" , "Narrow beam of light" , "Shaft of light" .)