Not filleted, as fish (4)
I believe the answer is:
bony
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not filleted as fish</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 bony that I've seen before include "With skeleton showing through" , "Skeletal" , "Scrawny" , "[GAUNT] ?" , "Angular" .)