Interrupter's sound (4)
I believe the answer is:
ahem
'interrupter's sound' 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 "Sound used to attract attention" , "request for attention" , "Half-cough to draw attention" , "attention-seeker?" , "Throat clearance to attract attention" .)