Related Clues:
- Aider and abettor; add-on
- Additional individual abetting criminal
- Provide something extra
- Extra-cost purchase
- Augment with
- Software module that enhances an existing application
- Charge hardware?
- Person who aids and abets a crime
- Extra notice given to teacher
- Item with an extra cost
- Extra exhaust put in and modified
- Maybe handbag thief's helper?
- Extra option
- Software extension