Declare Vera to be drunk (4)
I believe the answer is:
aver
'declare' is the definition.
(averring is a kind of declaring)
'vera to be drunk' is the wordplay.
'to be drunk' indicates anagramming the letters.
'vera' anagrammed gives 'AVER'.
(Other definitions for aver that I've seen before include "State firmly - don't rave" , "To declare or affirm solemnly as true" , "State decisively" , "State (to be the case)" , "say, with conviction" .)