The wrong party piece for a girl (5)
I believe the answer is:
Here is my best explanation:
'for a girl' is the definition.
'the wrong party' is the subsidiary indication.
'wrong' indicates an anagram.
'party' becomes 'ty' (I can't justify this - if you can you should believe this answer much more).
'the' anagrammed gives 'het'.
'piece' is the link.