Browning beef for beef stew?
The idea is to brown the outside of the meat in order to develop the flavour via the Maillard Reaction. This flavour will add to the richness and meatiness of the stew as a whole. Go ahead and give it a good crust. Don't overcrowd the pan or you will just end up steaming the meat in its own juices and it will never brown up: fry it in small batches instead.

Two hours braising in the stewing liquid will easily be enough to cook one-inch cubes of beef all the way through and will easily see off most nasty stuff.