Girl displaying knowledge in parties (7)
I believe the answer is:
dolores
'girl' is the definition.
'knowledge in parties' is the wordplay.
'knowledge' becomes 'lore' (lore is a kind of knowledge**).
'in' means one lot of letters goes inside another.
'parties' becomes 'dos' (do is a kind of party).
'lore' placed within 'dos' is 'DOLORES'.
'displaying' acts as a link.
(Other definitions for dolores that I've seen before include "Female" , "Lady" , "Old sore about girl" .)