Everyone in that place completely sane (3,5)
I believe the answer is:
all there
'completely sane' is the definition.
('not all there' can mean insane)
'everyone in that place' is the wordplay.
'everyone' becomes 'all' (all people).
'in that place' becomes 'there' (over there).
'all'+'there'='ALL THERE'
(Other definitions for all there that I've seen before include "right in the head" , "Everyone attending" , "The gate" , "Completely sane" , "Nothing missing" .)