Information contained in recording is mostly a shocker (4,3)
I believe the answer is:
data set
'information' is the definition.
(I've seen this before)
'contained in recording is mostly a shocker' is the wordplay.
I cannot quite understand how this works, but
'recording' could be 'dat' (DAT is an example) and 'dat' is located in the answer.
'a' is present in the answer.
The remaining letters 'set' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
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)" .)