Many agree it's new and in short supply (6)
I believe the answer is:
meagre
'short supply' is the definition.
Both the answer and definition are adjectives. Maybe there's an association between them I don't understand?
'many agree it's new' is the wordplay.
'many' becomes 'm' (Roman numeral for a thousand).
'it's new' is an anagram indicator.
'agree' anagrammed gives 'eagre'.
'm'+'eagre'='MEAGRE'
'and in' acts as a link.
Can you help me to learn more?
(Other definitions for meagre that I've seen before include "Lacking in quantity/quality" , "skinny" , "Scarce, not plentiful" , "little" , "Sparse" .)