A labyrinth intended to bring out adult's surprise (9)
I believe the answer is:
amazement
'surprise' is the definition.
(I've seen this before)
'a labyrinth intended to bring out adult's' is the wordplay.
'labyrinth' becomes 'maze' (synonyms).
'intended' becomes 'meant' (to mean something is to intend it).
'to bring out' suggests deleting specific letters.
'adult' becomes 'a' (abbreviation).
'meant' with 'a' taken away is 'ment'.
'a'+'maze'+'ment'='AMAZEMENT'
(Other definitions for amazement that I've seen before include "Stupefaction" , "Astonishment, wonderment" , "Incredulity" , "Shock" , "Astonished reaction" .)