Course right for boat (5)
I believe the answer is:
liner
'for boat' is the definition.
(I've seen this before)
'course right' is the wordplay.
'course' becomes 'line' (synonyms).
'right' becomes 'r' (abbreviation).
'line'+'r'='LINER'
(Other definitions for liner that I've seen before include "Large passenger vessel" , "Passenger transport" , "It covers bin's interior" , "Pleasure cruiser" , "Large passenger or cargo ship travelling on regular route" .)