Sociable old pirate going in sober (9)
I believe the answer is:
extrovert
'sociable' is the definition.
'old pirate going in sober' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'pirate' becomes 'rover' (I've seen this in another clue).
'going in' is an insertion indicator.
'sober' becomes 'tt' (I've seen this in other clues).
'rover' placed within 'tt' is 'trovert'.
'ex'+'trovert'='EXTROVERT'
(Other definitions for extrovert that I've seen before include "being for going out" , "Person who is more interested in the world than the inner self" , "A lively sociable person, always up front" , "party animal" , "Sociable, outgoing person" .)