Religious festival (6)
(Other definitions for fiesta that I've seen before include "Continental knees-up" , "public event abroad" , "Public whoopee in Spain" , "Latin American celebration" , "Public celebration in Spain" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">religious festival</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for easter that I've seen before include "Resurrection festival" , "Card, egg or Island" , "Christian celebration of the Resurrection" , "Christian festival of celebration" , "Egg-rolling time" .)