Duplicate parcel one lost (7)
I believe the answer is:
replica
'duplicate' is the definition.
(I've seen this in another clue)
'parcel one lost' is the wordplay.
'one' becomes 'i' (Roman numeral).
'lost' indicates an anagram.
'parcel'+'i'='parceli'
'parceli' is an anagram of 'REPLICA'.
(Other definitions for replica that I've seen before include "knock-off" , "Reproduction, exact copy" , "Perfect copy" , "Exact copy or model" , "Parcel I arranged as exact copy" .)