Using v7 your options are much more limited than they would be with newer software. That said, the Strip() function will help with this problem.
In the Table window, create a new Character calculated field. Assuming that your "xxx-xxxxxxxxxxxxxxx- x" value is in MyField, use the following for the formula:
This will remove all spaces from the field value.
Now hide MyField and arrange the field layout so that your new field appears in the same position.