Left port with a cargo (5)
I believe the answer is:
laden
'with a cargo' is the definition.
(I've seen this before)
'left port' is the wordplay.
'left' becomes 'l' (common abbreviation).
'port' becomes 'aden' (port in Yemen).
'l'+'aden'='LADEN'
(Other definitions for laden that I've seen before include "Put on board" , "charged a lot" , "Weighed down with much cargo" , "cargo aboard" , "full cargo ship" .)