Outer boundary (4)
'outer boundary' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for edge that I've seen before include "Intense quality; limit" , "Sharpness of mind" , "Border - meeting place" , "Rim - move gradually" , "Border - advantage" .)
'outer boundary' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for periphery that I've seen before include "Edge -- border" , "margin" , "Surrounding region" .)