"Pardon me" (4)
I believe the answer is:
ahem
'pardon me' 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 "Noise used to attract attention" , "call attracting attention" , "Half-cough to draw attention" , "Expression of disapproval" , "Sound made when clearing throat" .)