What is clean in irregular verbs?

There is no irregular verb of clean.

Clean is a regular verb, that is the past is formed by adding -ed to the Word eg cleaned.

Run is an irregular verb the past is not formed by adding -ed. The past is ran (a new Word)

Other examples:

regular: walk - walked, talked - talked, listen - listened, anticipate - anticipated

irregular - cut - cut, shoot - shot, give - gave, breed - bred