Polite interruption (4)
I believe the answer is:
ahem
'polite interruption' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ahem that I've seen before include "Utterance of mild disapproval" , "Excuse me!" , "Attention-grabbing expression" , "Gentle utterance to attract attention" , "Polite word to draw attention" .)