Beware of unfinished sparkling wine close to inebriate (4)
I believe the answer is:
cave
'beware' is the definition.
(old-fashioned term meaning 'look out')
'unfinished sparkling wine close to inebriate' is the wordplay.
'unfinished' means to remove the last letter.
'sparkling wine' becomes 'cava' (Spanish sparkling wine).
'close to' indicates one should take the final letters (the close/ending of).
The final letter of 'inebriate' is 'e'.
'cava' with its final letter taken away is 'cav'.
'cav'+'e'='CAVE'
'of' acts as a link.
(Other definitions for cave that I've seen before include "Hollow in a rock" , "Warning - grotto" , "Troglodyte's home" , "Primitive dwelling" , "Underground enclosure with surface access" .)