Liberal placed in sober group ultimately drinks, regrettably (4)
I believe the answer is:
alas
'regrettably' is the definition.
('alas' is said before regrettable news)
'liberal placed in sober group ultimately drinks' is the wordplay.
'liberal' becomes 'l' (abbreviation).
'placed in' indicates putting letters inside (I've seen this in other clues).
'sober group' becomes 'aa' (short for Alcoholics Anonymous).
'ultimately' says to take the final letters.
The last letter of 'drinks' is 's'.
'l' put inside 'aa' is 'ala'.
'ala'+'s'='ALAS'
(Other definitions for alas that I've seen before include "Expression of regret" , "Cry of regret" , "-- and alack!" , "Archaic exclamation of sorrow or regret" , "By bad luck" .)