Affectedly pretty (4)
'affectedly pretty' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for twee that I've seen before include "Attractively quaint" , "Sentimentally sweet" , "Excessively quaint" , "Affectedly cute" , "rather quaint" .)
(Other definitions for chichi that I've seen before include "Precious or affected in style" , "Very chic and smart - twice?" , "Very smart and sophisticated" , "Pretentiously stylish" , "Affectedly trendy" .)