Translation:My older brother wears a suit at work.
Slightly more natural, but in this case I wouldn't quibble. "[Someone] wears a suit at work" is not unheard-of. "The office" might make this sound more natural ("Do you wear a suit at the office?") but that might just be my ears.
I probably wouldn't take the "changes clothes at work" meaning unless they were talking about a radiation suit.