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' indicates putting letters inside (some letters go outside others).
'empty' says to hollow out the word (remove centre letters).
'palace' with its centre taken out is 'pe'.
'only' placed around '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." .)