A girl's jocular retort (5)
I believe the answer is:
sally
'retort' is the definition.
(I've seen this in another clue)
'a girl's jocular' is the wordplay.
'a girl' becomes 'Sal' (feminine given name).
'jocular' becomes 'ly' (I can't justify this - if you can you should give a lot more credence to this answer).
'sal'+'ly'='SALLY'
Can you help me to learn more?
(Other definitions for sally that I've seen before include "Charge" , "Sortie; witty retort" , "Girl" , "- - Lunn, flat cake" , "Rush out suddenly" .)