After the beginning was first taken aback (8)
I believe the answer is:
startled
'taken aback' is the definition.
(startling is a kind of taking aback)
'after the beginning was first' is the wordplay.
'after' is a charade indicator (letters next to each other).
'the beginning' becomes 'start' (start is a kind of beginning).
'was first' becomes 'led' (to lead is to go first).
'start' next to 'led' is 'STARTLED'.
(Other definitions for startled that I've seen before include "Frightened or surprised suddenly" , "Taken by surprise" , "Taken aback" , "Suddenly alarmed" , "Frightened or suprised suddenly" .)