Inherited a northern castle? Oddly, that's about right (9)
I believe the answer is:
ancestral
'inherited' is the definition.
(I've seen this before)
'a northern castle? oddly that's about right' is the wordplay.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'oddly' indicates anagramming the letters (letters in an odd order).
'that's about' indicates putting letters inside.
'right' becomes 'r' (common abbreviation).
'castle' with letters rearranged gives '[castle]'.
'n'+'[castle]'='n[castle]'
'ncestal' placed around 'r' is 'ncestral'.
'a'+'ncestral'='ANCESTRAL'
(Other definitions for ancestral that I've seen before include "by old relations" , "Coming down the tree" , "To do with forebears, say stately home" , "Belonging to the house" , "from old-timers" .)