Imitation subject to ridicule (4)
I believe the answer is:
mock
'to ridicule' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for mock that I've seen before include "Deride - false" , "Jeer, deride" , "Not real, ridicule" , "Make fun of; imitation" , "Treat with contempt -- imitation" .)