Announced some details initially about gallery (6)
I believe the answer is:
stated
'announced' is the definition.
(thesaurus)
'some details initially about gallery' is the wordplay.
'initially' suggests taking the first letters.
'about' means one lot of letters goes inside another.
'gallery' becomes 'tate' (I've seen this before).
The first letters of 'some details' is 'sd'.
'sd' placed around 'tate' is 'STATED'.
(Other definitions for stated that I've seen before include "Expressed in speech or writing" , "Uttered, expressed in words" , "Expressed in written or spoken words" , "Specified" , "Put in words, said" .)