Unfriendly for a party city (4)
I believe the answer is:
dour
'unfriendly' is the definition.
(thesaurus)
'a party city' is the wordplay.
'a party' becomes 'do' (do is a kind of party).
'city' becomes 'ur'.
'do'+'ur'='DOUR'
'for' is the link.
(Other definitions for dour that I've seen before include "Uncompromising" , "Grim, morose" , "Stern and severe looking" , "Sullen - unyielding" , "Obstinate - grim" .)