Up to the B in "beverage" (4)
I believe the answer is:
able
'up to' is the definition.
(I've seen this in another clue)
'b in beverage' is the wordplay.
'in' is an insertion indicator.
'beverage' becomes 'ale' (ale is a kind of beverage).
'b' going inside 'ale' is 'ABLE'.
'the' is the link.
(Other definitions for able that I've seen before include "Competent, capable" , "... was I ere I saw Elba (palindrome)" , "Having the ability to do something" , "Competent and equipped" , "Fully competent" .)