Extremely amusing (9)
I believe the answer is:
hilarious
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">extremely amusing</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for hilarious that I've seen before include "A scream" , "Extremely funny" , "Priceless!" , "Extremely amusing" , "Uriah's oil (anag.)" .)