Security racket relates to Protection all along The Border (8)
I believe the answer is:
hedgerow
'the border' is the definition.
(I've seen this before)
'security racket' is the wordplay.
'security' becomes 'hedge' (hedge is a kind of security).
'racket' becomes 'row' (I can't justify this - if you can you should believe this answer much more).
'hedge'+'row'='HEDGEROW'
'relates to protection all along' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for hedgerow that I've seen before include "rural boundary" , "Greenery between fields" , "Line of entwined bushes and trees" , "Field boundary" , "Living boundary between fields" .)