Egypt is regularly overturning complaint (4)
I believe the answer is:
stye
'complaint' is the definition.
(stye is a kind of health problem)
'egypt is regularly overturning' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'overturning' says the letters should be written in reverse.
'egypt'+'is'='egyptis'
The alternate letters of 'egyptis' are 'eyts'.
'eyts' back-to-front is 'STYE'.
(Other definitions for stye that I've seen before include "Eye problem" , "Eyelid affliction" , "Inflammation around the eye" , "Eyelid problem" , "It pains viewer" .)