"What?" is Clint's immediate, gobsmacked reaction. "What do you-- How-- What happened?"

He manages, mostly, to keep it from sounding accusatory, even though part of his brain is screaming 'HOW COULD YOU LET THAT HAPPEN???' loud enough to drown out most of his other thoughts. He might act like a little shit to Tron sometimes, but he trusts the guy, and knows logically that if he could've done anything, he would've. Same as Clint.