American lawyer raised challenge about a source of information (4,3)

I believe the answer is:

data set

I'm a little stuck... Click here to teach me more about this clue!

'source of information' is the definition.
'data set' can be an answer for 'information' (I've seen this before). I am unsure of the 'source of' bit.

'american lawyer raised challenge about a' is the wordplay.
'american lawyer' becomes 'DA' (abbreviation for 'District Attorney').
'raised' shows that the letters should be reversed in order (going up in a down clue).
'challenge' becomes 'test' (I've seen this in another clue).
'about' is an insertion indicator.
'test' enclosing 'a' is 'tesat'.
'tesat' in reverse letter order is 'taset'.
'da'+'taset'='DATA SET'

Can you help me to learn more?

(Other definitions for data set that I've seen before include "collected info" , "file" , "Collection of information (in computing)" .)

I've seen this clue in The Times.

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