Left in river beginning to expire, he's put out (8)
I believe the answer is:
deportee
'he's put out' is the definition.
(someone who's been deported)
'left in river beginning to expire' is the wordplay.
'left' becomes 'port' (left side of a ship - opposite of starboard).
'in' indicates putting letters inside.
'river' becomes 'dee' (River Dee).
'beginning to' says to take the initial letters.
The first letter of 'expire' is 'e'.
'port' placed within 'dee' is 'deporte'.
'deporte'+'e'='DEPORTEE'
(Other definitions for deportee that I've seen before include "Expelled foreigner" , "Person expelled from the home country" , "One ejected" , "Person sent back to land of origin" , "One expelled from a country" .)