Rump cooked rare (4)
I believe the answer is:
rear
'rump' is the definition.
(I've seen this before)
'cooked rare' is the wordplay.
'cooked' indicates an anagram.
'rare' with letters rearranged gives 'REAR'.
(Other definitions for rear that I've seen before include "Bring up - the tail" , "Rump" , "early, long before now" , "Bottom" , "Rise up at the back" .)