Large public room (6)
I believe the answer is:
saloon
'large public room' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for saloon that I've seen before include "Bar room" , "US bar - type of car" , "Car; public room" , "An American pub, as in the wild west" , "Boozer or shape of car" .)