Overly confident guidance systems set up on the borders (4)

I believe the answer is:

smug

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'overly confident' is the definition.
(I've seen this in another clue)

I can't explain the rest of the clue.

(Other definitions for smug that I've seen before include "Self-satisfied about gums" , "Self-satisfied, complacent" , "Self-righteous" , "irritating expression" , "Arrogantly complacent" .)

I've seen this clue in The Irish Times and the Irish Times (Crosaire).

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