Steal back to take one off the island (6)
I believe the answer is:
borneo
'the island' is the definition.
(Borneo is an example)
'steal back to take one off' is the wordplay.
'steal' becomes 'rob' (robbing is a kind of stealing**).
'back' says the letters should be written backwards.
'to take' means one lot of letters go next to another.
'off' indicates anagramming the letters.
'rob' in reverse letter order is 'bor'.
'one' with letters rearranged gives 'neo'.
'bor'+'neo'='BORNEO'
(Other definitions for borneo that I've seen before include "Oberon on the large Asian island" , "The world's third-largest island" , "Largest island of the Malay archipelago" , "Island, part of the Malay archipelago" , "Island containing Brunei" .)