Cross about North Carolina following rules? That’s unthinking (13)
I believe the answer is:
'unthinking' is the definition.
(both can mean selfish or thoughtless)
'cross about north carolina following rules?' is the wordplay.
'cross' becomes 'irate' (both can mean angry).
'about' is an insertion indicator.
'north carolina' becomes 'nc' (this could be a standard abbreviation which I don't know about).
'following rules?' becomes 'onside' (eg following the off-side rule in football).
'irate' going around 'nconside' is 'INCONSIDERATE'.
'that's' is the link.
(Other definitions for inconsiderate that I've seen before include "Thoughtlessly hurtful" , "rude" , "Lacking regard for the feelings of others" , "Without regard for the feelings of others" , "showing no regard for others" .)