Regulation record in ancestral houses (9)
I believe the answer is:
ordinance
'regulation' is the definition.
('ordinance' can be a synonym of 'regulation')
'record in ancestral houses' is the wordplay.
'houses' says the answer is hidden in the clue (part of the clue houses the answer).
'ORDINANCE' is hidden within 'record in ancestral'.
(Other definitions for ordinance that I've seen before include "religious service maybe" , "Regulation" , "Bill" , "law" , "Command" .)