Panic about cans, initially in short supply (6)
I believe the answer is:
scarce
'in short supply' is the definition.
(I've seen this before)
'panic about cans initially' is the wordplay.
'panic' becomes 'scare' (synonyms).
'about' indicates putting letters inside.
'initially' indicates taking the first letters.
The first letter of 'cans' is 'c'.
'scare' placed around 'c' is 'SCARCE'.
(Other definitions for scarce that I've seen before include "Rare shock Conservative getting in" , "Hard to get" , "Not enough to meet demand" , "Scant, meagre" , "Insufficient to meet demand" .)