The sole catlike creature in the house (11)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
plantagenet
'house' is the definition.
(historical royal house)
'the sole catlike creature' is the wordplay.
'the sole' becomes 'planta' (I've seen this before).
'catlike creature' becomes 'genet' (I've seen this before).
'planta'+'genet'='PLANTAGENET'
'in the' is the link.
(Other definitions for plantagenet that I've seen before include "royal dynasty" , "Former English royal family" , "9 [HOUSE]" , "Member of English royal house from Henry II to Richard III" .)