In very short supply (4)
I believe the answer is:
rare
'in very short supply' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rare that I've seen before include "Very infrequent or scarce" , "Rear up, being scarce" , "Infrequent; remarkable" , "Very lightly cooked, meat say" , "Might a four-leaf clover be so" .)