Girl at a fete (4)
I believe the answer is:
gala
'fete' is the definition.
(I've seen this before)
'girl at a' is the wordplay.
'girl' becomes 'gal' ().
'at' is a charade indicator (letters next to each other).
'gal'+'a'='GALA'
(Other definitions for gala that I've seen before include "Carnival, fete" , "Festive entertainment" , "Festive performance" , "sporting event" , "Festivity - celebration" .)