Let say I have Hive Mind in game:
The opponent casts Counterspell on my creature spell. Can I counter the Counterspell with the clone of Counterspell I get from Hive Mind?
In more detail, what happens is this:
You cast your creature spell, which let's say is a Weirded Vampire. (Why would you be playing Weirded Vampire against Hive Mind? Weird, huh.) The stack is
Your opponent casts Counterspell, and Hive Mind's ability triggers. The stack is
The ability resolves, giving you a copy of Counterspell, which you can choose to have target the original Counterspell. The stack is
Your Counterspell resolves, countering your opponent's Counterspell. The stack is
The Weirded Vampire now resolves.
This does mean that (in a 2-player game) Hive Mind basically nullifies any counterspell which can target a copy of itself.