Holiday season, for short (4)
I believe the answer is:
xmas
'holiday season for short' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for xmas that I've seen before include "Yuletide" , "Brief version of the Nativity, beginning with Greek letter" , "annual holiday" , "Short for Christmas" , "Christmas (informal)" .)