assure · verb T /əˈʃʊr/
assure
B2 to tell someone confidently that something is true, especially so that they do not worry
Dictionary example:
She assured him (that) the car would be ready the next day.
Learner example:
I can assure you that the food will be delicious. (First Certificate in English; B2; Greek)
assure (MAKE CERTAIN)
C1 to make something certain to happen
Dictionary example:
This loan should assure the company's future.
Learner example:
The PT is guaranteed to assure higher test results or your money back! (Certificate in Advanced English; C1; Russian)