Sociable old commie holding vicar up (9)
I believe the answer is:
extrovert
'sociable' is the definition.
'old commie holding vicar up' is the wordplay.
'old' becomes 'ex'.
'commie' becomes 'trot' (short for Trotskyite).
'holding' means one lot of letters goes inside another.
'vicar' becomes 'rev'.
'up' says the letters should be written backwards (in down clue: letters go upwards).
'rev' back-to-front is 'ver'.
'trot' enclosing 'ver' is 'trovert'.
'ex'+'trovert'='EXTROVERT'
(Other definitions for extrovert that I've seen before include "Lively and outgoing person" , "Sociable, outgoing person" , "Outgoing (personality)" , "Outgoing type" , "Outgoing rather than inward-looking" .)