Directly state:
* Declare
* Assert
* State
* Affirm
* Pronounce
Be open and honest:
* Confess
* Admit
* Reveal
* Disclose
Be straightforward:
* Explain
* Clarify
* Articulate
* Communicate
Be positive and supportive:
* Compliment
* Praise
* Encourage
* Celebrate
The best antonym will depend on the specific meaning of "insinuate" in the context. For example, if someone is insinuating something negative, you might use an antonym like "compliment" or "praise" to express the opposite.
Let me know if you have a specific example in mind, and I can help you choose the most appropriate antonym.