Hail Queen for State (4)
I believe the answer is:
aver
'for state' is the definition.
(both can mean to declare)
'hail queen' is the wordplay.
'hail' becomes 'ave' (greeting in Latin).
'queen' becomes 'r' (abbreviation for regina, e.g. in ER ).
'ave'+'r'='AVER'
(Other definitions for aver that I've seen before include "Say firmly, rave if necessary" , "State firmly, perhaps rave" , "State firmly and positively" , "Declare or insist" , "To declare or affirm solemnly as true" .)