Trip for one in old-fashioned vessel (6)
I believe the answer is:
cruise
'trip' is the definition.
(I know that cruise is a more specific form of the action navigate)
'one in old-fashioned vessel' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
'vessel' could be 'cruse' (cruse is a kind of vessel) and 'cruse' is found within the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'for' is the link.
Can you help me to learn more?
(Other definitions for cruise that I've seen before include "Sea trip" , "Pleasure trip on ship" , "Coast" , "Holiday at sea" , "Tom, say" .)