Drink one before church and fix date (4,3)
I believe the answer is:
iced tea
'drink' is the definition.
(I've seen this before)
'one before church and fix date' is the wordplay.
'one' becomes 'i' (Roman numeral).
'before' means one lot of letters go next to another.
'church' becomes 'ce' (abbreviation for Church of England).
'and' says to put letters next to each other.
'fix' is an anagram indicator.
'date' is an anagram of 'dtea'.
'i'+'ce'+'dtea'='ICED TEA'
(Other definitions for iced tea that I've seen before include "Cool drink" , "Cold summer drink" , "Chilled drink" .)