Citadel changed, in a manner of speaking (7)
I believe the answer is:
dialect
'in a manner of speaking' is the definition.
(I've seen this before)
'citadel changed' is the wordplay.
'changed' indicates an anagram.
'citadel' is an anagram of 'DIALECT'.
(Other definitions for dialect that I've seen before include "Regional form of speech" , "Talk of the district" , "Local language variation" , "Local language variant" , "Local lingo" .)