Recording medium — a duo worked with it to get copy (9)
I believe the answer is:
audiotape
'recording' is the definition.
(audiotape is a kind of recording)
'a duo worked with it to get copy' is the wordplay.
'worked with' is an anagram indicator.
'to get' indicates putting letters inside.
'copy' becomes 'ape' (ape can mean to copy or imitate).
'duo' anagrammed with 'it' can make 'udiot'.
'a' inserted within 'udiot' is 'audiot'.
'audiot'+'ape'='AUDIOTAPE'
'medium' is the link.
(Other definitions for audiotape that I've seen before include "recording" , "record" .)