Stare wildly after English holiday (6)
I believe the answer is:
easter
'holiday' is the definition.
(Easter is a Christian holiday)
'stare wildly after english' is the wordplay.
'wildly' indicates anagramming the letters.
'after' says to put letters next to each other.
'english' becomes 'e' (abbreviation).
'stare' is an anagram of 'aster'.
'aster' after 'e' is 'EASTER'.
(Other definitions for easter that I've seen before include "Teaser (anag.)" , "Annual religious festival" , "holiday time" , "Resurrection festival" , "Christian festival of celebration" .)