This is the documentation of JSU for Jira Cloud. If you are using JSU on Jira Server or on Jira Data Center, you can find the documentation here.
The 'Clear Field Value' post-function clears any field, after a transition has been completed. This can be a system- or a custom field.
The field can be on the issue in transition(within same issue) or on a related issue, like a sub-task, a linked issue or an issue within an Epic (during the transition on the Epic).
You can add any number of fields to perform the clear operation.
You can clear the value of any specified field. Click the + Button to add additional fields to your configuration.
A workflow is configured so that the 'Close' transition has the '"Copy Value From Other Field" post-function to clear any field. The function is configured to clear the 'Security Level' field. If a user closes an issue on this workflow, the value of the 'Security Level' field will be cleared.