Amusing behaviour (6)
I believe the answer is:
antics
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">amusing behaviour</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 antics that I've seen before include "'Capers, pranks (6)'" , "Clowning" , "extraordinary goings-on" , "Absurd or foolish movements intended to amuse" , "Movements intended to be amusing, pranks" .)