Echo up in refurbished citadel (9)
I believe the answer is:
duplicate
'echo' is the definition.
(thesaurus)
'up in refurbished citadel' is the wordplay.
'in' indicates putting letters inside.
'refurbished' indicates anagramming the letters.
'citadel' with letters rearranged gives 'dlicate'.
'up' placed inside 'dlicate' is 'DUPLICATE'.
(Other definitions for duplicate that I've seen before include "An exact copy" , "Increase twofold" , "replica" , "Copy - teacup lid (anag)" , "Double" .)