Like blue lobsters (4)
I believe the answer is:
rare
'like blue lobsters' 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 "Special" , "like gold dust" , "Not easily come by like undercooked meat" , "Exceptional" , "Might a four-leaf clover be so" .)