A vessel, by the sound of it, to make money (4)
I believe the answer is:
earn
'make money' is the definition.
(to earn is to make money)
'a vessel by the sound of it' is the wordplay.
'a vessel' becomes 'urn' (urn is a type of container).
'by the sound of it' shows a homophone (sound like).
'urn' sounds like 'EARN'.
'to' acts as a link.
(Other definitions for earn that I've seen before include "Get (money) for work or labour" , "Be paid for work" , "Acquire by one's efforts" , "and 3: Work for bed and board" , "Gain through labour or work" .)