Keep to the north of port (5)
I believe the answer is:
haven
'port' is the definition.
(both can mean a place of safety)
'keep to the north' is the wordplay.
'keep' becomes 'have' (I've seen this in other clues).
'to the north' becomes 'N' (abbreviation).
'have'+'n'='HAVEN'
'of' acts as a link.
(Other definitions for haven that I've seen before include "Place of safety or sanctuary" , "Sheltered port" , "Refuge; harbour" , "Harbour, small port" , "A peaceful refuge" .)