Complex sentence: After a brief fight, Blart overpowers and handcuffs Veck, but Kent pulls his gun on Blart by revealing himself as a mole in the SWAT team and had worked with Veck for the whole time.
Split into simpler sentences: After a brief fight, Blart overpowers and handcuffs Veck. However, Kent pulls his gun on Blart, revealing himself as a mole in the SWAT team who had been working with Veck the whole time.