Make-up artist? (4)
I believe the answer is:
liar
'make-up artist?' is the definition.
(I've seen this in another clue)
'make-up artist?' is the wordplay.
'make' becomes 'li' (I can't justify this - if you can you should give a lot more credence to this answer).
'up' is a reversal indicator (in down clue: letters go upwards).
'artist?' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'ra' in reverse letter order is 'ar'.
'li'+'ar'='LIAR'
Can you help me to learn more?
(Other definitions for liar that I've seen before include "One whose pants are on fire?" , "Fabricator" , "one trying to sell pork pies" , "Perjuror" , "Teller of fibs" .)