Pentecost (7)
I believe the answer is:
whitsun
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pentecost</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 whitsun that I've seen before include "Holy Spirit festival" , "Period seven weeks after Easter" , "Wins hut on short Christian Sabbath" , "Feast" , "Pentecost season" .)