Hedge set around borders (5)
I believe the answer is:
edges
'borders' is the definition.
(an edge is a border or margin)
'hedge set around' is the wordplay.
'around' indicates the answer is hidden within the clue.
'EDGES' is hidden within 'hedge set'.
(Other definitions for edges that I've seen before include "They're used for cutting" , "Outer limits" , "Slowly moves" , "Boundaries of a surface" , "Borders, rims" .)