Depraved about testamentary certification (9)

I believe the answer is:

reprobate

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'depraved' is the definition.
(I know that depraved can be written as reprobate)

'testamentary certification' is the wordplay.
'testamentary' becomes 're' (I can't explain this - if you can you should give a lot more credence to this answer).
'certification' becomes 'probate' (probate is a kind of certification).
're'+'probate'='REPROBATE'

'about' acts as a link.

Can you help me to learn more?

(Other definitions for reprobate that I've seen before include "someone depraved" , "immoral" , "Rogue" , "Ne'er-do-well" , "Rascal" .)

I've seen this clue in The Irish Independent.

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