Sadly Liberal placed in sober group ultimately drinks (4)
I believe the answer is:
alas
'sadly' is the definition.
(I've seen this before)
'liberal placed in sober group ultimately drinks' is the wordplay.
'liberal placed in sober group' becomes 'ala' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ultimately' says to take the final letters.
The last letter of 'drinks' is 's'.
'ala'+'s'='ALAS'
Can you help me to learn more?
(Other definitions for alas that I've seen before include "'- Poor Yorick' (Hamlet)" , "Too bad, so sad" , "Sad expression" , "By bad luck" , "Cry of grief" .)