One accepted first neurotic complaint (4)
I believe the answer is:
acne
'complaint' is the definition.
(acne is a kind of disease)
'one accepted first neurotic' is the wordplay.
'one' becomes 'ace' ('ace' can be a synonym of 'one'**).
'accepted' indicates putting letters inside.
'first' says to take the initial letters.
The first letter of 'neurotic' is 'n'.
'ace' going around 'n' is 'ACNE'.
(Other definitions for acne that I've seen before include "Inflammation of glands in skin" , "Pimply skin condition of adolescence" , "Cane for the teenager?" , "Teenage spots" , "Skin disorder" .)