Complete dismissal of a cockney's charity (3-3-3)
I believe the answer is:
out-and-out
'complete' is the definition.
(I've seen this before)
'dismissal of a cockney's charity' is the wordplay.
'dismissal of' becomes 'out' (I can't explain this - if you can you should give a lot more credence to this answer).
'a cockney's charity' becomes 'andout' ('handout' - handout is a kind of charity - said with a cockney accent, dropping the 'H').
'out'+'andout'='OUT-AND-OUT'
Can you help me to learn more?
(Other definitions for out-and-out that I've seen before include "Absolute; completely" , "In every respect" , "Utter and thorough - never in" , "Utter, absolute" , "Thorough, surpassing" .)