Productive compound in effect must include iodine (9)
I believe the answer is:
efficient
'productive' is the definition.
(thesaurus)
'compound in effect must include iodine' is the wordplay.
'compound' indicates an anagram.
'must include' means one lot of letters goes inside another.
'iodine' becomes 'I' (chemical symbol).
'in'+'effect'='ineffect'
'ineffect' is an anagram of 'efficent'.
'efficent' going around 'i' is 'EFFICIENT'.
(Other definitions for efficient that I've seen before include "Effective, competent" , "Businesslike" , "Performing with little wastage" , "Effective in doing what is required" , "Producing results with little waste of effort" .)