Add [artistname] to [trackname] / Merge fields

Hi all, sorry if this is covered. My over-tired brain is failing at google right now.

What i want to do is:
Add [artist] to [title] with a separator of ' - ' (space dash space) so i get:

Why would i do this?
Well, i've decided i wanted to re-tag a compilation to have the comp title as the artist, and add the artist to the track title field.

Yes, at least dozens of times. And also in the FAQs

Instead of xyz (as in the FAQs) use %artist% - %title%.

Yes, why indeed? It would be much more sensible to leave the title as title-only and the artist as artist-only as it is very hard to separate them again.
Put the artist into the %artist% field and think of a decent name for the %band% tag.
Then: if you MUST add the artist to the title and want to have an easier option to cut the artist again later, use a separator, that is usually not included in everyday language like the underscore _
If you later search for a pattern within the title then everything in front of the underscore shows the artist, everything behind it represents the title.
As the dash often is part of the title, you may get funny results.