Top-class puzzle: wow! (5)

I believe the answer is:

amaze

I'm a little stuck... Click here to teach me more about this clue!

'wow' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

(Other definitions for amaze that I've seen before include "Greatly surprise in a labyrinth" , "Dumbfound" , "Cause wonder" , "Bewilder" , "Bowl over" .)

I've seen this clue in The Sun.

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