Online Dictionaries:
* Merriam-Webster: [https://www.merriam-webster.com/](https://www.merriam-webster.com/)
* Oxford English Dictionary: [https://www.oed.com/](https://www.oed.com/)
* Dictionary.com: [https://www.dictionary.com/](https://www.dictionary.com/)
* Thesaurus.com: [https://www.thesaurus.com/](https://www.thesaurus.com/)
* WordHippo: [https://www.wordhippo.com/](https://www.wordhippo.com/)
These websites provide comprehensive definitions and lists of synonyms and antonyms for various words.
Printed Dictionaries and Thesauruses:
* Webster's New World College Dictionary: This is a popular and widely available dictionary that includes a section for synonyms and antonyms.
* Roget's Thesaurus: A classic thesaurus that provides a vast collection of synonyms and antonyms, organized by categories.
Other Resources:
* Google Search: You can simply search for "antonym for clever" on Google, and it will provide a list of potential antonyms.
* Wordreference: [https://www.wordreference.com/](https://www.wordreference.com/) This website offers a variety of language resources, including dictionaries and thesauruses.
It's important to note that the "best" antonym for "clever" will depend on the specific context in which you are using the word. Consider the nuances of the situation and choose the antonym that most accurately reflects the opposite meaning you are trying to convey.