Nobles offering no Government access (5)
I believe the answer is:
entry
'access' is the definition.
(entry is a kind of access)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for entry that I've seen before include "Debut" , "Doorway" , "Competitors - way in" , "field" , "Way in; item in list" .)