Clever, like Pharaoh, leader of Egypt (6)
I believe the answer is:
astute
'clever' is the definition.
(astute means sharp or clever)
'like pharaoh leader of egypt' is the wordplay.
'like' becomes 'as'.
'pharaoh' becomes 'tut' (Tutankhamun, the ancient Egyptian pharaoh).
'leader of' indicates taking the first letters.
The first letter of 'egypt' is 'e'.
'as'+'tut'+'e'='ASTUTE'
(Other definitions for astute that I've seen before include "Sharp and clever" , "Discerning" , "Shrewd, canny" , "Smart and canny" , "Able to make accurate assessments" .)