"I'm standing right here" (4)
I believe the answer is:
ahem
'i'm standing right here' 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" , "call attracting attention" , "I say!" , "Polite noise to draw attention" , "Half-cough to draw attention" .)