Is this the position prince takes when disowned by royal family for being improper? (9*)
I believe the answer is:
out of line
Here is my best explanation:
'improper?' is the definition.
'is this the position prince takes when disowned by royal family' is the subsidiary indication.
I cannot really see how this works, but
'family' could be 'line' (I've seen this before) and 'line' is present in the answer.
This may be the basis of clue (or it may be nonsense).
'for being' is the link.
(Other definitions for out of line that I've seen before include "Beyond the accepted bounds of one's position or authority - crooked?", "impudent", "Exhibiting unacceptable behaviour" and "Behaving badly".)