XML : How to remove a space in XML using stylesheet using RegEx

I have an XML and I am looking for finding particular tag (in this case "FirstName") and removing space in the value only if there is a - character before the space.

In other words, I want to keep spaces if there is no - front of them. I want to do this using an XSL stylesheet with RegEx matching and replace function.

Expected result is Sam-Louise, removing space between "Sam-" and "Louise"

  <?xml version="1.0" encoding="utf-8"?>  <NCV Version="1.14">      <Invoice>          <customer>              <customerId>12785</customerId>              <FirstName>Sam- Louise</FirstName>              <LastName>Jones</LastName>          </customer>      </Invoice>  </NCV>