Want costly article reduced (6)
I believe the answer is:
dearth
'want' is the definition.
(both can mean a lack or scarcity)
'costly article reduced' is the wordplay.
'costly' becomes 'dear' (synonyms).
'article' becomes 'the' (the definite article in English).
'reduced' means to remove the last letter.
'the' with its last letter taken away is 'th'.
'dear'+'th'='DEARTH'
(Other definitions for dearth that I've seen before include "Hatred (anag) -- shortage" , "deficiency" , "Scarcity of thread" , "want" , "Insufficient amount" .)