Just outside empty palace without concealment (6)
I believe the answer is:
openly
'without concealment' is the definition.
(I've seen this before)
'just outside empty palace' is the wordplay.
'just' becomes 'only' (synonyms).
'outside' means one lot of letters goes inside another.
'empty' suggests removing the centre.
'palace' with its centre taken out is 'pe'.
'only' enclosing 'pe' is 'OPENLY'.
(Other definitions for openly that I've seen before include "In an overt way" , "In candid, up-front manner" , "without secrecy" , "In frank and candid manner" , "Candidly, without concealment." .)