Declare sadly a tunic's been appropriated by old queen (10)
I believe the answer is:
annunciate
'declare' is the definition.
(thesaurus)
'sadly a tunic's been appropriated by old queen' is the wordplay.
'sadly' indicates anagramming the letters.
'been appropriated by' indicates putting letters inside.
'old queen' becomes 'anne' (Queen Anne).
'a'+'tunic'='atunic'
'atunic' anagrammed gives 'unciat'.
'unciat' inserted inside 'anne' is 'ANNUNCIATE'.
(Other definitions for annunciate that I've seen before include "Announce (arch.)" , "Proclaim" .)