Another's wrecked in part of Atlantic (5,3)
I believe the answer is:
north sea
'part of atlantic' is the definition.
('North Sea' is part of 'atlantic')
'another's wrecked' is the wordplay.
'wrecked' indicates an anagram.
'anothers' anagrammed gives 'NORTH SEA'.
'in' is the link.
(Other definitions for north sea that I've seen before include "UK source of natural gas" , "Expanse of water" , "It's not land to our East" , "Waters east of the UK" , "Water beside UK" .)