Before you start get a full load of health packs, shivs and stun guns from NY Associate Level. A full load on these jobs takes about 2000 energy points.
I didn't bother to load up with grenades in Vegas.
Now attack Red Jackson.
First use your stun guns to destroy her henchman.
Then use all your shivs and remaining stun guns to weaken Red. After using all your shivs and stun guns attack her twice.
This attack will obliterate your henchmen and partially weaken you.
Use healthpacks to regain full health and attack once more.
This time you will be crushed.
Now leave Vegas and refill your shivs, stun guns and health in NY Associate level.
Again, this will take about an hour and 2000 energy points...be patient - even if there are "dry periods", the average amount of energy used to refill the consumables will be around 2000 energy points.
(Hint: set repeatjob for 1 to 3 second delay and dont bother banking... you are now at 0 health and no-one can attack you anyway).
Once you have a full load of shivs etc, go back to the Vegas District 5 and attack again exactly as described above
It took me 3 cycles of doing this to destroy her.
Remember: each time you press attack in Vegas she regenerates 25% - even if you run away - so dont go in unless you have a full load of health, shivs and stun guns.
Depending on your energy levels you may need to refill energy - I needed 2 refills.