It happens (5)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">it happens</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 event that I've seen before include "celebration?" , "contest in programme" , "Happening, noteworthy perhaps" , "game, perhaps" , "A thing taking place" .)
(Other definitions for fit that I've seen before include "Certified OK by the doctor" , "Of suitable quality" , "In good physical shape 93)" , "Healthy; spasm" , "Apt" .)