Perform the following steps to add processing logic after a workflow transition is executed:

1. Select and edit the workflow to configure.
2. Select the Diagram mode.
3. Create a new workflow transition that will take the issue out of the Frozen status to another status.
4. Click on the Post functions link for the newly created transition.
5. Click on Add post function, select Clear Field Value (JSU) from the list, and click on Add.
6. Select the Reason for Freezing field from Field, and click on the Add button.
7. Click on Publish Draft to apply the change.

With the post function in place, after you have executed the transition, the Reason for Freezing field will be cleared out. You can also see from the issue's change history, as part of the transition execution, where the Status field is changed from Frozen to Open, the change for the Reason for Freezing field is also recorded.