Replace hanger bar of rear derailleur

[EngiNerd]

I broke the hanger bar on my mtb and am having trouble loosing the hex connection to the derailleur.  I only have a shorter Allen wrench, say 5" leg, but even so putting about all I can into it it won't loosen.  I worried I am doing something wrong.  YouTube videos gloss over this part and they always show a typical hex bolt to be removed, but the connection on mine is different, the hex inlet for the Allen wrench is inside the clip if that makes sense.  I have never loosened a connection like this but imagine it is the standard "lefty loosey." Check out the pics for a better idea of what I'm talking about.

Basically I'm posting just to make sure I approaching this right and not going to mess up the derailleur by putting too much muscle into it.  Thanks

[Blatant]

Yes, it's lefty loosey. Some SRAM stuff is 25mm torx, but that looks like a standard 5mm. You don't have anything to spin against since the hanger is broken. Just put some monkey torque on it. Worst case, you destroy the derailleur, which appears to have seen better days itself.

[EngiNerd]

Unfortunately this monkey has yet to produce enough torque.  Just doesn't seem right that it hasn't broken loose but the awakard shape of the derailleur does make it hard to spin against.  I'll borrow a vice tomorrow