What does the british slang term hold on a tick mean?

"Hold on a tick" is a British slang phrase meaning "wait a moment" or "just a second". It's a casual way to ask someone to pause briefly, similar to "hold on" or "hang on" in American English.

The word "tick" in this context is a shortened form of "second", referring to a short amount of time. So, "hold on a tick" is essentially asking someone to wait for a very short period.