Excellent red at dinner (4)
I believe the answer is:
rare
'excellent' is the definition.
(I've seen this in another clue)
'red at dinner' is the wordplay.
'red' becomes 'r' (I've seen this in other clues).
'at dinner' becomes 'are' (I can't explain this - if you can you should give a lot more credence to this answer).
'r'+'are'='RARE'
Can you help me to learn more?
(Other definitions for rare that I've seen before include "Not common" , "Occurring infrequently" , "Scarcely seen" , "Seldom encountered" , "(Of meat) red" .)