Duplicator initially needs it to copy (5)
I believe the answer is:
ditto
'copy' is the definition.
(thesaurus)
'duplicator initially needs it to' is the wordplay.
'initially' says to take the initial letters.
'needs' is a charade indicator (letters next to each other).
The first letter of 'duplicator' is 'd'.
'd'+'it'+'to'='DITTO'
(Other definitions for ditto that I've seen before include "Two small marks indicating the same again" , "that which has been said" , "Copy" , "In lists, the same again with two small marks" , "Repeat the word(s) above" .)