Declare forcefully (6)
I believe the answer is:
assert
(Other definitions for assert that I've seen before include "Declare, profees" , "State firmly, aver" , "Declare, state vigorously" , "Swear" , "State firmly or vigorously" .)
I believe the answer is:
assert
(Other definitions for assert that I've seen before include "Declare, profees" , "State firmly, aver" , "Declare, state vigorously" , "Swear" , "State firmly or vigorously" .)