Start talk holding one drink (9)
I believe the answer is:
originate
'start' is the definition.
('originate' can be a synonym of 'start')
'talk holding one drink' is the wordplay.
'talk' becomes 'orate' (orating is a kind of talking).
'holding' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'drink' becomes 'gin' (gin is a kind of drink**).
'i'+'gin'='igin'
'orate' enclosing 'igin' is 'ORIGINATE'.
(Other definitions for originate that I've seen before include "pioneer" , "Bring into existence" , "Invent" , "Cause to begin, be the first" , "Set up" .)