Unsightly rug left at yard not right (4)
I believe the answer is:
ugly
'unsightly' is the definition.
(similar in meaning)
'rug left at yard not right' is the wordplay.
'rug left' becomes 'ug' (I am not sure about this - if you are sure you should believe this answer much more).
'at' means one lot of letters go next to another.
'yard' becomes 'y' (abbreviation).
'not right' becomes 'L' (short for left - ie not right).
'y' after 'l' is 'ly'.
'ug'+'ly'='UGLY'
Can you help me to learn more?
(Other definitions for ugly that I've seen before include "Extremely unattractive" , "Offensive to one's sight or other senses" , "Unpleasing to the eye" , "Lacking in beauty" , "Difficult to look at" .)