[wp-hackers] changing the tag query results

[Haluk Karamete]

When the site visitor clicks on a tag term (such as "Apple"), he will
normally be taken to a url such as

"site.com/tag/apple" where wordpress returns all posts that have been
tagged as "apple".

Assuming the the visitor was on "Fruits" category when he clicked on an an
"apple" tag ( out of an excerpt of a post or something), and you want to
filter down the results to those posts that's been tagged as "apple" but
only if the post is in "fruits" category, what do you need to do to that
URL?