It’s for you once to enter (5)
I believe the answer is:
foyer
'it's' is the definition.
I can't judge whether this definition defines the answer.
'for you once to enter' is the wordplay.
'you once' becomes 'ye' (archaic version of 'you').
'to enter' means one lot of letters goes inside another.
'for' placed around 'ye' is 'FOYER'.
Can you help me to learn more?
(Other definitions for foyer that I've seen before include "Theatre public area" , "Entrance hallway" , "Theatre's entrance hall" , "Reception room or waiting area" , "Hotel entrance hall" .)