Traditionally the No.1 provider of net protection (10)
I believe the answer is:
goalkeeper
'provider of net protection' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps there's a link between them I don't understand?
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for goalkeeper that I've seen before include "Seaman was one" , "Given, say" , "Given one of these" , "A Greek pole (anag.)" .)