Ape, Siamese perhaps, or parrot? (7)
I believe the answer is:
copycat
'parrot?' is the definition.
(parrot is a kind of copycat)
'ape siamese perhaps' is the wordplay.
'ape' becomes 'copy' (synonyms).
'siamese perhaps' becomes 'cat' (siamese is a kind of cat).
'copy'+'cat'='COPYCAT'
'or' is the link.
(Other definitions for copycat that I've seen before include "Plagiarist possibly" , "Highly imitative" , "Slavish imitator" , "Person (or crime) imitating another" , "One who imitates another" .)