Country girl on the vessel (6)
I believe the answer is:
canada
'country' is the definition.
(Canada is an example)
'girl on the vessel' is the wordplay.
'girl' becomes 'ada' ().
'on' is a charade indicator (letters next to each other).
'the vessel' becomes 'can' (type of container).
'ada' after 'can' is 'CANADA'.
(Other definitions for canada that I've seen before include "Weight units" , "part of the world" , "World's second-largest country by area" , "- Balsam; - goose" , "North American goose" .)