Is the movement sideways or does the sprocket turn on the wheel ie rotate a bit.
Sideways movement means sprocket carrier bearings are worn and you shouldnt really ride it.
Take the back wheel out and the carrier should come out by hand.
Put the axle back in through the carrier and lever the axle around to see exactly where the movement is.
You can write down the numbers on the bearings and order them directly from bearing shop, cheaper than genuine.
Sideways movement means sprocket carrier bearings are worn and you shouldnt really ride it.
Take the back wheel out and the carrier should come out by hand.
Put the axle back in through the carrier and lever the axle around to see exactly where the movement is.
You can write down the numbers on the bearings and order them directly from bearing shop, cheaper than genuine.