Explained what was formerly battered (9)

I believe the answer is:

expounded

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'explained' is the definition.
(I've seen this before)

'formerly battered' is the wordplay.
'formerly' becomes 'ex'.
'battered' becomes 'pounded' (I am not sure about this - if you are sure you should believe this answer much more).
'ex'+'pounded'='EXPOUNDED'

'what was' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for expounded that I've seen before include "made clear" , "Explained" , "commented on" .)

I've seen this clue in the Sydney Morning Herald.

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