Uncommon and not at all well done (4)
I believe the answer is:
rare
I believe this is a double definition.
'uncommon' is the first definition.
(similar in meaning)
'not at all well done' is the second definition.
(I've seen this in another clue)
'and' acts as a link.
(Other definitions for rare that I've seen before include "(Of meat) red" , "little done?" , "may be bloody" , "Infrequent; remarkable" , "Scarce or uncommon" .)