Course right for a vessel (5)
I believe the answer is:
liner
'a vessel' is the definition.
(liner is a kind of vessel)
'course right' is the wordplay.
'course' becomes 'line' ('line' can be a synonym of 'course').
'right' becomes 'r' (common abbreviation).
'line'+'r'='LINER'
'for' acts as a link.
(Other definitions for liner that I've seen before include "Material applied to inner surface" , "that's found in the kitchen bin, perhaps" , "bin-bag?" , "Commercial ship" , "Passenger transport" .)