Newly-developed porcelain lacking no imitation (7)
I believe the answer is:
replica
'imitation' is the definition.
(thesaurus)
'newly-developed porcelain lacking no' is the wordplay.
'newly developed' indicates an anagram.
'lacking' is a deletion indicator.
'porcelain' with 'no' taken away is 'prcelai'.
'prcelai' with letters rearranged gives 'REPLICA'.
(Other definitions for replica that I've seen before include "Exact copy as of sport trophy" , "Perfect copy" , "Parcel I arranged as exact copy" , "Reproduction, exact copy" , "Parcel I found with exact copy" .)