Crossword Genius

Shock when peeper gets key (3-6)

Ross

I believe the answer is:

eye-opener

'shock' is the definition.
(thesaurus)

'peeper gets key' is the subsidiary indication.
'peeper' becomes 'eye' ('eye' can be a synonym of 'peeper').
'gets' says to put letters next to each other.
'key' becomes 'opener' (I've seen this before).
'eye'+'opener'='eyeopener'

'when' is the link.

(Other definitions for eye-opener that I've seen before include "Circumstances that brings surprise and enlightenment" , "Fact that surprises or enlightens in optical way" , "Fact or circumstance that brings enlightenment and surprise" , "Something startling" , "This surprises greatly - makes you look" .)

I've seen this clue in The Guardian and The Telegraph.
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