Baddie’s extremely useful vessel given position in Rome once (10)
I believe the answer is:
consulship
'position in rome once' is the definition.
(position in ancient Rome)
'baddie's extremely useful vessel given' is the wordplay.
'baddie's' becomes 'con's' (con can mean a convict).
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'vessel' becomes 'ship' (ship is a kind of vessel).
'given' says to put letters next to each other.
'useful' with its middle taken out is 'ul'.
'cons'+'ul'+'ship'='CONSULSHIP'
(Another definition for consulship that I've seen is " office in Rome".)