Peek or peer (4)
I believe the answer is:
look
I believe this clue is a double definition.
'peek' is the first definition.
(I've seen this in another clue)
'peer' is the second definition.
(I've seen this before)
(Other definitions for look that I've seen before include "Behold" , "Get an eyeful" , "Direct one's gaze towards" , "Facial expression" , "Watch, observe" .)