Vessel of note, heading off (3)
I believe the answer is:
ark
'vessel' is the definition.
(ark is a kind of vessel)
'note heading off' is the wordplay.
'note' becomes 'mark' ('mark' can be a synonym of 'note').
'heading off' means to remove the first letter.
'mark' with its initial letter taken off is 'ARK'.
'of' is the link.
(Other definitions for ark that I've seen before include "Noah's ship" , "Coffer" , "-- of the Covenant" , "Noah's boat" , "Large vessel" .)