Trade in lead production (4)
I believe the answer is:
'trade in' is the definition.
'lead production' is the wordplay.
'production' indicates an anagram.
'lead' is an anagram of 'DEAL'.
(Other definitions for deal that I've seen before include "Soft wood; trade" , "Act of business" , "Plank of softwood timber" , "Agreement; soft wood" , "Agreement; hand out cards" .)