So out of the DB01 box there is no clutch.
A clutch is available as a hop-ups and the manual recommends using one if using modified or high power brushless. Curiously there is a 'single' and a 'double' slipper available. As far as I know, the single allows only the spur gear to slip, whereas the double allows the two drive belt pulleys to slip independently of the spur gear.
I picked up the double slipper from eBay - here's the parts. Wow.