Trick or gull (6)
I believe the answer is:
outwit
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">trick</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">gull</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">or</span>' acts as a link.<br/ ></span>
(Other definitions for outwit that I've seen before include "Outfox" , "Be too clever for, get the better of" , "Dupe" , "Show more ingenuity than" , "Hoodwink" .)