Express disapproval of Egyptian king repeatedly (3-3)
I believe the answer is:
tut-tut
'express disapproval' is the definition.
(sound expressing disapproval)
'egyptian king repeatedly' is the wordplay.
'egyptian king' becomes 'tut' (Tutankhamun, the ancient Egyptian pharaoh).
'repeatedly' indicates the doubling of some letters.
'tut' doubled is 'TUT-TUT'.
'of' acts as a link.
(Other definitions for tut-tut that I've seen before include "Words of disapproval" , "Repetitive exclamation of disapproval or annoyance" , "Noise of disapproval" , "Mild exclamation of disapproval" , "Expression of disapproval - a repetitive palindrome" .)