Attention-getter
I think it could be either:
'attention-getter' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for psst that I've seen before include "Interjection to draw attention" , "Beckoning sound" , "Sound of call to hear a secret" , "attempt to make secret contact" , "Listen!" .)
'attention-getter' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ahem that I've seen before include "It's said to gain attention; ah, me (anag.)" , "Cough to draw attention" , "call attracting attention" , "Sound used to attract attention" , "Throat clearance to attract attention" .)