While this is not an available option OOTB, if you are interested in moving the "create an idea" option to the top of the action widget there are a few options available to you.
1. If you would like to see this as an available option in a future release I would encourage you to create an idea in the Ideas for Jive space where our Product Managers review top rated ideas for possible inclusions into future releases.
2. If you are interested in customizing this feature yourself I would recommend reaching out to the Jive Developers community here in the Jive Community where you can collaborate with other developers on interested features.
3. If you would like assistance developing customizations for your instance our Professional Services team can assist in determining the scope of the project and developing a customization which meets your use case. If you are interested in this option please file a case in your Jive Community's custom group and we can set-up an engagement for you.