Parasite urges corn production (9)
I believe the answer is:
scrounger
'parasite' is the definition.
(thesaurus)
'urges corn production' is the wordplay.
'production' indicates anagramming the letters.
'urges'+'corn'='urgescorn'
'urgescorn' is an anagram of 'SCROUNGER'.
(Other definitions for scrounger that I've seen before include "bum" , "Freeloader" , "Sponge" .)