Spots in part of East London, as locals may pronounce it? (4)
I believe the answer is:
'spots' is the definition.
(skin condition causing spots)
I don't understand the rest of the clue.
(Other definitions for acne that I've seen before include "Inflammation of glands in skin" , "Skin problem, mainly of teenagers" , "Pimply skin condition of adolescence" , "Pimply ailment of adolescnce" , "sort of disease" .)