Very lightly cooked (4)
I believe the answer is:
rare
'very lightly cooked' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rare that I've seen before include "Seen once in a blue moon" , "Unusual - exquisite" , "Exceptionable" , "thin on the ground" , "Infrequent; remarkable" .)