Repartee of comedienne, perhaps, becomes wasted (7)
I believe the answer is:
withers
'becomes wasted' is the definition.
I can't judge whether this defines the answer.
'repartee of comedienne' is the wordplay.
'repartee' becomes 'wit' (I've seen this before).
'of comedienne' becomes 'hers' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'wit'+'hers'='WITHERS'
'perhaps' acts as a link.
Can you help me to learn more?
(Other definitions for withers that I've seen before include "Part between a horse's shoulder blades" , "Ridge at the base of a horse'd neck, from which its height is measured" , "Bit of a nag" , "Writhes on ridge between a horse's shoulder-blades" , "dies slowly" .)