Torn parcel containing one copy (7)
I believe the answer is:
'copy' is the definition.
(I know this)
'torn parcel containing one' is the wordplay.
'torn' indicates an anagram.
'containing' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'parcel' anagrammed gives 'replca'.
'replca' going around 'i' is 'REPLICA'.
(Other definitions for replica that I've seen before include "Parcel I used to contain exact copy" , "knock-off" , "I parcel (anag) - reproduction" , "Parcel I arranged as exact copy" , "Parcel I found with exact copy" .)