Realise rubbish left out is not so problematic (6)
I believe the answer is:
easier
'realise rubbish left out is not' is the definition.
I can't judge whether this definition defines the answer.
'so problematic' is the wordplay.
I cannot really see how this works, but
'so' could be 'as' (e.g. phrases like 'not as tall' and 'not so tall') and 'as' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for easier that I've seen before include "Posing less difficulty" , "More facile" , "more like a piece of cake" , "Simpler" , "More comfortable or less difficult" .)