One takes care rubbish is swept up after New Year (7)
I believe the answer is:
janitor
'one takes care' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'rubbish is swept up after new year' is the wordplay.
'rubbish' becomes 'rot' (both can mean nonsense).
'is swept up' says the letters should be written in reverse (in a down clue, letters go up).
'after' is a charade indicator (letters next to each other).
'new year' becomes 'jani' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'rot' backwards is 'tor'.
'tor' put after 'jani' is 'JANITOR'.
Can you help me to learn more?
(Other definitions for janitor that I've seen before include "(In Scotland) school caretaker" , "Caretaker or doorkeeper" , "Caretaker (mainly US)" , "One employed to clean and maintain a building" , "Person looking after building" .)