In general, man accepts calendar (7)
I believe the answer is:
almanac
'calendar' is the definition.
(I've seen this before)
'in general man accepts' is the wordplay.
'in' says the answer is hidden in the clue.
'ALMANAC' can be found hidden inside 'general man accepts'.
(Other definitions for almanac that I've seen before include "Calendar listing astronomical events etc" , "Annual publication providing information like Old Moore's" , "Sailor's or farmer's calendar" , "Annual publication with mixed data, forecasts etc." , "Kind of year-book like Old Moore's" .)