Artist's concealing this woman's skin problems (6)
I believe the answer is:
rashes
'skin problems' is the definition.
'artist's concealing this woman's' is the wordplay.
'artist's' becomes 'ras' (Royal Academician's abbreviation).
'concealing' is an insertion indicator.
'this woman' becomes 'she' (**).
'ras' going around 'she' is 'RASHES'.
(Other definitions for rashes that I've seen before include "Shares with pimply outbreaks" , "Outbreaks of spots on skin" , "Red eruptions of the skin" , "Skin marks caused by allergies etc" , "Eruptions of spots on the skin" .)