Illness that's just here as some New Yorkers may say (13)
I believe the answer is:
indisposition
'illness' is the definition.
(I know that indisposition is a type of illness)
'here as some new yorkers may say' is the wordplay.
I cannot really see how this works, but
'as' could be 'in' (I've seen this in other clues) and 'in' is present in the answer.
'new' could be 'n' (common abbreviation eg NT for New Testament) and 'n' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'that's just' is the link.
Can you help me to learn more?
(Other definitions for indisposition that I've seen before include "State of being unwell or unfit" , "Disinclination" , "Slight illness" .)