Spurious imitation (4)
I believe the answer is:
sham
'spurious imitation' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sham that I've seen before include "Counterfeit or insincere" , "Not what it seems to be" , "'Fake, pseudo (4)'" , "Pretence; bogus, false" , "False and phoney" .)