What part of speech is the word clean?

Answer 1

"Cleaned" is the past tense or past participle form of the base verb "clean". As with all other verbs, the participle can function in a sentence as an adjective, as in the sentence "A cleaned gun makes a better impression than a poorly maintained one."

Answer 2

Either adjective or verb: "Is your room clean?" {adjective} or "Clean your room before going out." {verb}