Winds of Chaos

Is there a way to increase a character's toughness, if said character hasn't got it available to them in their career? E.g. wizard.

Read the "Non-Career Advancement" box at the top of page 48. It says yes you can, but it costs double XP.
It also recommends GM approval.

Thank you

Yep. Spend your downtime endeavor getting into barfights, and losing...repeatedly.