There appears to be is a carriage return (ASCII 13) at the end of the quote.
So what I would do is copy the clipboard to a text variable (T1); calculate the position of ASCII 13 in T1 (N1); copy from character 0 to character N1 in T1, and assign it to T2; and then copy T2 to the clipboard.
Variable Set to ASCII Char 13 to %T% // This is the Ascii code for a carriage return
Variable Set String %T% from the clipboard contents
Variable Set Integer %N% to the position of "%T%" in %T%
Variable Modify String: Copy a substring in %T%, starting at 0 and %N% characters long to %T%
Variable Modify String: Save %T% to the clipboard
You will likely need to tweak the code slightly. I haven't thoroughly tested the code.
Also, I did this with Macro Express Pro, so the syntax will be a little different with Macro Express 3.