Surprise in a labyrinth (5)
I believe the answer is:
amaze
'surprise' is the definition.
(I know that amaze is a type of surprise)
'a labyrinth' is the wordplay.
'labyrinth' becomes 'maze' (synonyms).
'a'+'maze'='AMAZE'
'in' is the link.
(Other definitions for amaze that I've seen before include "Bewilder" , "Stun" , "Startle" , "Flummox" , "Surprise greatly, astonish" .)