One friend keeps it as copy (7)
I believe the answer is:
imitate
'copy' is the definition.
(synonyms)
'one friend keeps it' is the wordplay.
'one' becomes 'I' (Roman numeral).
'friend' becomes 'mate' (mate is a kind of friend).
'keeps' means one lot of letters goes inside another.
'mate' enclosing 'it' is 'mitate'.
'i'+'mitate'='IMITATE'
'as' is the link.
(Other definitions for imitate that I've seen before include "Take as a model" , "Copy or mimic" , "Copy, simulate" , "Copy (mannerisms)" , "Parrot" .)