Unlock the Puzzle: Open the Clue with a Penknife

The answer to the crossword question “Open with a penknife, say” is SLIT. This refers to the action of using a penknife to make a narrow opening or incision in something, such as a piece of paper or fabric. The word “say” in the clue indicates that the answer is a verb and “open with a penknife” provides additional context to narrow down the possible options. Therefore, SLIT is the most appropriate word that matches the given description and fits into the crossword.