Vessel has lover on it: one of the crew? (9)
I believe the answer is:
boatswain
'one of the crew?' is the definition.
(member of a boat's crew)
'vessel has lover' is the wordplay.
'vessel' becomes 'boat' (boat is a kind of vessel).
'has' says to put letters next to each other.
'lover' becomes 'swain' (old-fashioned term for a lover).
'boat'+'swain'='BOATSWAIN'
'on it' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for boatswain that I've seen before include "Crew member" , "Warrant officer in charge of a ship's crew" , "Seaman" , "In brief, he's a bosun" , "who has a pipe with a mate?" .)