Proclaim 650 are to receive final notice (7)
I believe the answer is:
declare
'proclaim' is the definition.
(I know that declare is a type of proclaim)
'650 are to receive final notice' is the wordplay.
'650' becomes 'dcl' (I've seen this in another clue).
'to receive' indicates putting letters inside.
'final' indicates one should take the final letters.
The final letter of 'notice' is 'e'.
'dcl'+'are'='dclare'
'dclare' enclosing 'e' is 'DECLARE'.
(Other definitions for declare that I've seen before include "Make a statement, to customs perhaps" , "Profess" , "Announce 13 closed" , "... cut short innings" , "Announce formally" .)