Spirit of a royal house (7)
I believe the answer is:
bourbon
I believe this is a double definition.
'spirit' is the first definition.
'royal house' is the second definition.
(Bourbon is an example)
'of a' is the link.
(Other definitions for bourbon that I've seen before include "Rye whiskey" , "Henry of Navarre, for one" , "Whiskey - biscuit" , "Corn whiskey" , "A drink" .)