Little fish (7)
I believe the answer is:
tiddler
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">little fish</span>' is the definition.<br/ ><span class="explanation-format__explanation">(tiddler can mean a small fish)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for tiddler that I've seen before include "One small" , "Small fry" , "Small thing" , "Tiny fish, child" , "Minnow" .)