How to copy part of one tag and insert in another tag

I need to replace part of the Album tag with part of the Title Tag. How can I do this?

Using the Replace with regular expression I don't appear to be able to reference any field other than the one to be changed. I can locate both fragments with regular expressions.

Thanks.

You can do this in different ways, e. g. using a third temporary tagfield.
One possible solution could be using this scheme.
With ALBUM = "A B C" and TITLE = "D E F" you will get "ALBUM = "A E C".

Actiontype 5: Format tag field
Field: ALBUM
Formatstring: $regexp(%ALBUM%,(.) (.) (.),$1 $regexp(%TITLE%,(.) (.) (.),$2) $3)

DD.20090708.0909.CEST

Thanks Detlev for your prompt and helpful reply. Worked fine.

Just to clarify, which fields, if any, in the Replace with Regular Expressions action can functions like $regexp be used?