Use charm to engage captain that is needed around vessel (9)
I believe the answer is:
captivate
'use charm to engage' is the definition.
(to captivate someone is to charm them)
'captain that is needed around vessel' is the wordplay.
'captain' becomes 'capt' (abbreviation).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'needed around' is an insertion indicator.
'vessel' becomes 'vat' (vat is a kind of vessel).
'ie' enclosing 'vat' is 'ivate'.
'capt'+'ivate'='CAPTIVATE'
(Other definitions for captivate that I've seen before include "Delight" , "Fascinate completely" , "Enchant" , "Charm" , "Entrance" .)