Fake barrier doesn't open (9)
I believe the answer is:
imitation
'fake' is the definition.
(synonyms)
'barrier doesn't open' is the wordplay.
'barrier' becomes 'limitation'.
'doesn't open' means to remove the first letter.
'limitation' with its initial letter removed is 'IMITATION'.
(Other definitions for imitation that I've seen before include "it's not for real" , "Act of copying" , "Copy of an authentic article" , "take-off" , "Mock -- ersatz" .)