Unusual way to serve meat (4)
I believe the answer is:
rare
'unusual' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for rare that I've seen before include "(Of meat) red" , "Might steak be" , "Rear up, being scarce" , "Scarce as hen's teeth!" , "Very infrequent, lightly cooked" .)