Princes, for example, demanding author’s share of profits (7)
I believe the answer is:
Here is my best explanation:
This clue might be a double definition.
'princes for example' is the first definition.
'profits' is the second definition.
'demanding author's share of' is the link.
This may not be right. Some or all of it may belong to one of the definitions.
(Other definitions for royalty that I've seen before include "People on thrones?", "Payment for use of work", "Top people; type of payment", "Those of the monarchy", "Queens, emperors, etc", "Majestic quality", "King or queen's status", "Author's perquisite", "Queen?" and "percentage earned".)