Sloshed parent drinking whiskey and port (7)
I believe the answer is:
antwerp
'port' is the definition.
(Belgian port)
'sloshed parent drinking whiskey' is the wordplay.
'sloshed' indicates anagramming the letters.
'drinking' means one lot of letters goes inside another (inserted letters are consumed or drunk).
'whiskey' becomes 'W' (phonetic alphabet: alpha, bravo, charlie etc.).
'parent' anagrammed gives 'anterp'.
'anterp' enclosing 'w' is 'ANTWERP'.
'and' acts as a link.
(Other definitions for antwerp that I've seen before include "Van Dyck birthplace" , "harbour" , "New part of Dutch city" , "foreign city" , "North Belgian port" .)