A certain old head of state making announcements (12)
I believe the answer is:
declarations
'announcements' is the definition.
(I have seen 'Official announcements' mean 'declarations' so perhaps 'announcements' could also mean 'declarations')
'a certain old head of state making' is the wordplay.
'head of' suggests taking the first letters.
'making' is an anagram indicator.
The first letter of 'state' is 's'.
'a'+'certain'+'old'+'s'='acertainolds'
'acertainolds' is an anagram of 'DECLARATIONS'.
(Other definitions for declarations that I've seen before include "statements" , "Announcement" , "Official announcements" .)