How can we hide a specific Subcategory option from the Subcategory choice list on the Incident form

We have a business requirement on the Incident form to hide one specific Subcategory option when the Category is set to Application. Both fields (Category and Subcategory) are standard choice fields on the Incident table.

We cannot deactivate this Subcategory choice at the dictionary level because:

• The same Subcategory is still needed and actively used in other forms and processes, and
• We are creating a new Catalog Item where this Subcategory must remain visible under the Application category by default.

Because of this, the Subcategory must remain active, but it should be hidden only on the Incident form when Category = Application. All other Subcategory choices must remain available.

Can anyone advise on the best approach to achieve this?