As a report, it takes me aback (4)
I believe the answer is:
item
'as a report' is the definition.
I can't judge whether this defines the answer.
'it takes me aback' is the wordplay.
'takes' is a charade indicator (letters next to each other).
'aback' is a reversal indicator.
'me' in reverse letter order is 'em'.
'it'+'em'='ITEM'
Can you help me to learn more?
(Other definitions for item that I've seen before include "Separate object or unit" , "Report" , "Unit; detail" , "One thing - two people, perhaps" , "Loving couple" .)