Excessively quaint (4)
I believe the answer is:
twee
'excessively quaint' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for twee that I've seen before include "Small and sweet (colloq.)" , "Precious - sentimental" , "Excessively quaint" , "Small and pretty" , "Sentimentally pretty" .)