Making Spent Time a required field when editing an issue?

Does anyone know if there is a way to make Spent Time a required field when editing an issue? I would love to be able to edit this in the workflow, but can't find any way to do so. Even if anytime a user edited an issue there was a spent time required field it would be great. Is there an easy plugin for this? or an easy hack I can make to do this?

Cheers