@ToBiku: You could use the following to get just whatever is in the title before the colon:
Code:
{title:sublist(0,1,:)}
But, I tend to agree with the others. Looking at my library, anything with a colon in the title would be meaningless without what is after the colon. Or a duplicate title.
It also depends on why you are doing this. If your library has a lot of books like your example, where what is after the colon is more of a subtitle, then I would split it.
If the problem is that the file name length, you can look at the template function "shorten". With this you have a bit of control over how the title is shortened to fit. I think calibre is using this on the file names if the full path is going to exceed 254 characters (I think it's 254).