Served up sample of desserts specifically used to catch one's attention (4)
I believe the answer is:
psst
'to catch one's attention' is the definition.
I can't tell whether this defines the answer.
'served up sample of desserts specifically' is the wordplay.
'served up' shows that the letters should be reversed in order (in a down clue, going upwards).
'sample of' says the answer is hidden in the clue (an extract or sample of the clue).
'tssp' is hidden in the letters of 'desserts specifically'.
'tssp' written backwards gives 'PSST'.
'used' acts as a link.
Can you help me to learn more?
(Other definitions for psst that I've seen before include "Sibilant sound to attract attention furtively" , "Listen!" , "Sound to call quietly" , "Sibilant interjection to call attention" , "way of attracting attention" .)