Cry in the bath about cake Prue initially discarded (6)
I believe the answer is:
eureka
'cry in the bath' is the definition.
'eureka' can be an answer for 'cry' (I have seen 'Cry of success ' mean 'eureka' so perhaps 'cry' could also mean 'eureka'). I'm not certain of the 'in the bath' bit.
'about cake prue initially discarded' is the wordplay.
'about' says the letters should be written backwards.
'cake' becomes 'ake' (I am not sure about this - if you are sure you should believe this answer much more).
'initially discarded' means to remove the first letter (the initial letter is discarded).
'prue' with its first letter removed is 'rue'.
'ake'+'rue'='akerue'
'akerue' in reverse letter order is 'EUREKA'.
Can you help me to learn more?
(Other definitions for eureka that I've seen before include "Exclamation of discovery by Archimedes" , "Cry on a great discovery" , ""I've found it!" (Archimedes)" , "Discovery announcement" , "Exultant cry" .)