Lives concerned with borders (7)
I believe the answer is:
resides
'lives' is the definition.
(to reside somewhere is to live there)
'concerned with borders' is the wordplay.
'concerned with' becomes 're' (re can mean regarding or about).
'borders' becomes 'sides' (I've seen this in another clue).
're'+'sides'='RESIDES'
(Other definitions for resides that I've seen before include "stays in Peebles" , "Lives, dwells" , "Sojourns" , "stayed in Scotland" , "stays required" .)