Not year-round (8)
I believe the answer is:
seasonal
'not year-round' is the definition.
('seasonal' is the opposite to 'year-round')
This is the entire clue.
(Other definitions for seasonal that I've seen before include "depending on the month" , "Appropriate to the time of year" , "Occurring at certain times of the year" , "For a particular period" , "Like an Easter egg" .)