Hard to look at (4)
I believe the answer is:
ugly
'hard to look at' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ugly that I've seen before include "not tasty?" , "Extremely unattractive" , "Far from beautiful" , "Unprepossessing, repulsive" , "Disquieting" .)