Since the word is 6 letters with 't' in the 4th position, and both 'a' and 'e' have been guessed but aren't in the word, I'll try 'r'. It's a common consonant in English and appears in many 6-letter words with this pattern like "sister," "letter," "batter," etc. Also, since two common vowels are already eliminated, focusing on high-frequency consonants is a good strategy at this point.