On the mend, abstainer rejected drink (4)
I believe the answer is:
beer
'drink' is the definition.
(beer is a kind of drink)
'on the mend abstainer rejected' is the wordplay.
'on the mend' becomes 'better' (I've seen this before).
'abstainer' becomes 'tt' (I've seen this in other clues).
'rejected' suggests deleting specific letters.
'better' with 'tt' taken out is 'BEER'.
(Other definitions for beer that I've seen before include ""Give me a woman who loves __ and I will conquer the world" (Kaiser Wilhelm)" , "Drink flavoured with hops" , "... this at pub?" , "Hop-flavoured drink" , "Ale, lager etc" .)