Very shortly before he was killed OTL by Milo, Publius Clodius Pulcher had an altercation with former ally Mark Antony, who was now sleeping with his wife at the time. To quote Goldsworthy:
"His old quarrel with Clodius reignited and on one occasion a sword-armed Mark Antony let a group that chased him into a bookshop. Clodius barricaded himself inside and managed to repel the attack, but Cicero was probably right to claim that only this prevented his murder."
So what if Clodius had not managed this and died there and then at Antony's hand? I can think of two big changes: one, Milo not being the culprit means he can pursue his political career further; two, Antony being the culprit means he may not make it to join Caesar's legions in Gaul. The latter has a very good chance of turning the Battle of Alesia into a defeat for Caesar, which of course has massive implications of its own.
What do you guys think?