Fish; fingerprint (3)
I believe the answer is:
dab
<span class="explanation-format__ClueExplanation">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">(dab is a type of fish)</span><br/ ><br/ >'<span class="explanation-format__original">fingerprint</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for dab that I've seen before include "Apply small amounts (usually a liquid) to a surface" , "Apply light touches of colour to the fish" , "Lightly press" , "Flatfish; fingerprint" , "Bad kind of fish" .)