Because one's wrong about the time of year (6)
I believe the answer is:
season
'the time of year' is the definition.
('season' can be a synonym of 'time of year')
'because one's wrong about' is the wordplay.
'because' becomes 'as' (I've seen this in other clues).
'wrong' is an anagram indicator.
'about' indicates putting letters inside.
'ones' is an anagram of 'seon'.
'as' going within 'seon' is 'SEASON'.
(Other definitions for season that I've seen before include "Salt, maybe" , "Add salt, pepper, spices etc" , "Period of a year" , "Eg, summer" , "' - - of mists ...' (Keats)" .)