Note world shortage (6)
I believe the answer is:
dearth
'shortage' is the definition.
(dearth can mean a shortage or lack)
'note world' is the wordplay.
'note' becomes 'd' (musical note).
'world' becomes 'earth' (synonyms).
'd'+'earth'='DEARTH'
(Other definitions for dearth that I've seen before include "Severe shortage" , "Hatred (anag) -- shortage" , "Shortage, lack" , "Acute insufficiency" , "Red hat for scarcity" .)