Without a coat, Rufus, albeit uneasy, looks really lovely (9)
I believe the answer is:
beautiful
'lovely' is the definition.
(similar in meaning)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for beautiful that I've seen before include "Aesthetically very pleasing" , "Lovely" , "Attractive, good-looking" , "Visually pleasing" , "Very pleasing to the senses" .)