Lout into paintings about to have threesome (6)
I believe the answer is:
troika
'threesome' is the definition.
(I know that threesome can be written as troika)
'lout into paintings about' is the wordplay.
'lout' becomes 'oik' (I've seen this before).
'into' is an insertion indicator.
'paintings' becomes 'art' (painting is a type of artwork).
'about' shows that the letters should be reversed in order.
'art' back-to-front is 'tra'.
'oik' placed inside 'tra' is 'TROIKA'.
'to have' acts as a link.
(Other definitions for troika that I've seen before include "Russian three-horse coach" , "Three-horse Russian vehicle" , "Team of three" , "cart" , "Russian carriage pulled by three horses abreast" .)