Imitative person (4)
(Other definitions for copycat that I've seen before include "Person who imitates another in feline way" , "Emulator" , "Imitator - imitative" , "Ape" , "Person imitating another (or cloned pet?)" .)
'imitative person' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for aper that I've seen before include "One creating copies" , "copyist" .)