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' acts as a link.
(Other definitions for bourbon that I've seen before include "Rye whiskey" , "Henry of Navarre, for one" , "Whiskey - biscuit" , "Corn whiskey" , "A drink" .)