Shortage, paucity (6)
I believe the answer is:
dearth
This clue is a double definition.
'shortage' is the first definition.
(dearth can mean a shortage or lack)
'paucity' is the second definition.
(synonyms)
(Other definitions for dearth that I've seen before include "Acute insufficiency" , "In short supply" , "poverty" , "Shortage, lack" , "Acute shortage" .)