Turnstile (4)
I believe the answer is:
gate
'turnstile' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for gate that I've seen before include "Barrier, exit" , "Opening in a wall or fence" , "Facility in airport" , "Barrier - door" , "Number of people admitted to a sporting event" .)