Statistics collected together, a bit taken aback (4)
I believe the answer is:
data
'statistics collected' is the definition.
(I've seen this before)
'a bit taken aback' is the wordplay.
'bit' becomes 'tad' (both can mean a small amount).
'taken aback' is a reversal indicator.
'a'+'tad'='atad'
'atad' back-to-front is 'DATA'.
'together' acts as a link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for data that I've seen before include "Raw facts" , "intelligence" , "Series of measurements" , "Factual information" , "Organised information" .)