Modern milky coffee dairy brewed — I must go (6-3)
I believe the answer is:
latter-day
'modern' is the definition.
(I've seen this before)
'milky coffee dairy brewed i must go' is the wordplay.
I cannot quite see how this works, but
'coffee' could be 'latte' (I've seen this before) and 'latte' is located in the answer.
'i' could be 'a' and 'a' is present in the answer.
This explanation may well be incorrect...
(Other definitions for latter-day that I've seen before include "Contemporary" , "Church of Jesus Christ of ... Saints" , "Belonging to recent times" , "Mormons belong to The Church of the . . . . . .-. . . Saints" , "Modern" .)