Learn Turkish: Ev tamamen temiz. - The house is completely clean.

Just like çok and biraz, tamamen (completely) is a degree modifier. It goes directly before the adjective it describes, which is temiz (clean) here. You could easily swap it to say Ev çok temiz (The house is very clean) or Ev biraz temiz (The house is a little clean).

Where is the word for "is" in this sentence?

In Turkish, there is no separate word for "to be" (am/is/are) in the present tense. For a third-person subject like Ev (the house), you just place the subject and the adjective together. So, Ev temiz naturally means "The house is clean" without needing an extra verb.

Why does Ev translate to "The house" instead of "A house"?

Turkish does not have a direct word for "the." When a noun like Ev is the subject at the beginning of a sentence, it is usually understood as specific (the house). If you wanted to say "a house," you would use the word bir (a/one) and say Bir ev tamamen temiz.

Is tamamen related to the word tam (full/exact)?

Yes! Tam means full or complete. The word tamamen has an old Arabic ending (-en) that turns it into an adverb meaning "completely." While you will see this ending on a few common borrowed words, you cannot use it to make your own adverbs from native Turkish words.