Just arrived, establish secure island (12)
I believe the answer is:
newfoundland
'island' is the definition.
(Canadian island)
'just arrived establish secure' is the wordplay.
'just arrived' becomes 'new' (I've seen this in another clue).
'establish' becomes 'found' (found can mean to set up or establish).
'secure' becomes 'land' (I've seen this in another clue).
'new'+'found'+'land'='NEWFOUNDLAND'
(Other definitions for newfoundland that I've seen before include "Island off Canada" , "Large island part of Canada's most easterly province" , "Canadian province and island" , "Canadian province; breed of dog" , "Canadian isle and province" .)