Time of year celebrated by degrees (4)
I believe the answer is:
xmas
'time' is the definition.
(I have seen 'present time' mean 'xmas' so perhaps 'time' could also mean 'xmas')
'by degrees' is the wordplay.
'by' becomes 'x' (2 by 4 is 2 x 4).
'degrees' becomes 'MAs' (MA is an example).
'x'+'mas'='XMAS'
'of year celebrated' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for xmas that I've seen before include "Abbreviation for a winter festival" , "present time" , "annual holiday" , "Short celebration" , "Winter festival (informal)" .)