A nobleman's said to show up (6)
I believe the answer is:
appear
'show up' is the definition.
(both can mean to arrive)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for appear that I've seen before include "Develop" , "become available" , "Show up like ghost" , "Seem - come into view" , "Turn up" .)