One poor port returned to (4-3)
I believe the answer is:
have-not
'one poor' is the definition.
(poor person)
'port returned to' is the wordplay.
'port' becomes 'haven' (both can mean a place of safety).
'returned' says the letters should be written backwards.
'to' backwards is 'ot'.
'haven'+'ot'='HAVE-NOT'
(Other definitions for have-not that I've seen before include "Person of little material wealth" , "Deprived person" , "Someone who lacks possessions" , "Someone with meagre possessions" , "Poor person" .)