Scarcity of thread perhaps (6)
I believe the answer is:
'scarcity' is the definition.
(dearth is a kind of scarcity)
'thread perhaps' is the wordplay.
'perhaps' indicates anagramming the letters.
'thread' is an anagram of 'DEARTH'.
'of' acts as a link.
(Other definitions for dearth that I've seen before include "Lack of resources" , "Hatred (anag) -- shortage" , "Scarcity of thread" , "deficiency" , "In short supply" .)