Less attractive (6)
I believe the answer is:
uglier
'less attractive' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for uglier that I've seen before include "with worse features" , "More frightful" , "More offensive to look at" , "More unattractive or repellent to the eye" , "More displeasing to the sight" .)