Better start drinking after the last word (5)
I believe the answer is:
amend
'better' is the definition.
('amend' can be a synonym of 'better')
'start drinking after the last word' is the wordplay.
'start' suggests taking the first letters.
'after' means one lot of letters go next to another.
'the last word' becomes 'amen' (I've seen this before).
The first letter of 'drinking' is 'd'.
'd' put after 'amen' is 'AMEND'.
(Other definitions for amend that I've seen before include "Ameliorate" , "Correct or alter to improve" , "Rectify" , "Make minor changes to" , "Change for the better" .)