Has to be new wine (4)
I believe the answer is:
must
I believe this is a double definition.
'has to' is the first definition.
(I've seen this before)
'new wine' is the second definition.
(I've seen this in another clue)
'be' is the link.
(Other definitions for must that I've seen before include "Make off with (plane)" , "Smell of dampness or staleness" , "Prerequisite" , "Essential to have" , "Mould - grape juice during fermentation" .)