Fig.: to vigorously defend or support someone or something

Everybody thought his project was great but it was so risky financially that nobody went to bat for his proposal

Tutti pensavano che fosse un progetto molto valido, ma comportava grossi rischi finanziari, per cui nessuno si è sentito di spezzare una lancia in suo favore

I don't condone Tom's actions, but I will take up the cudgels for him because he's only ten

Non giustifico quello che ha fatto Tommaso, ma, visto che ha solo dieci anni, ho deciso di spezzare una lancia in suo favore

The origin of this expression is unknown. A cudgel being a short, thick stick that is often used as a weapon