Up, endlessly, producing wine (4)
I believe the answer is:
asti
'wine' is the definition.
(I've seen this before)
'up endlessly' is the wordplay.
'up' becomes 'astir' ('astir' can be a synonym of 'up').
'endlessly' means to remove the last letter.
'astir' with its final letter removed is 'ASTI'.
'producing' acts as a link.
(Other definitions for asti that I've seen before include "Alcohol" , "Piedmont wine city, SE of Turin" , "18" , "Piedmontese white wine" , "It's a (anag) - wine" .)