The most common and most likely answer to this crossword clue is the 11 letter word LETTERPRESS
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More clues leading to the result LETTERPRESS
Buddy explains!

The straight part
We know that "printed matter" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case printed matter = letterpress.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
Crossword Answer definitions
LETTERPRESS noun- The printing process in which ink is applied to the top surface of a raised image area, which is then pressed against paper to transfer the image.
- Printing directly from type, in distinction from printing from plates.
- A machine used for such printing.