House party in a rut, perhaps (5)
I believe the answer is:
tudor
'house' is the definition.
(royal house)
'party in a rut perhaps' is the wordplay.
'party' becomes 'do' (do is a kind of party).
'in' means one lot of letters goes inside another.
'perhaps' is an anagram indicator.
'rut' anagrammed gives 'tur'.
'do' placed inside 'tur' is 'TUDOR'.
(Other definitions for tudor that I've seen before include "Member of the dynasty ruling England 1485-1603" , "A royal house of England" , "Relating to the English ruling family in the 1500s" , "Owen's house" , "Former English royal house" .)