Twelve months (4)
'twelve months' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for year that I've seen before include "Complete cycle of seasons" , "One tenth of a decade" , "eg 2004" , "See 33 Across" , "Orbital period" .)
'twelve months' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for calendar year that I've seen before include "period of months?" , "January 1 to December 31 inclusive" , "Twelve months" .)