wheel bearings, balljoint, could be a few things but get it sorted asap.
its a lot cheaper to sort a problem before it gets worse, also if something is on its way out it will let go at the worse time, ie middle of nowhere or on the move.
it could be something small but for piece of mind take it into a garage and get it checked, dont want to worry you but its better to be safe than sorry
easiest thing is to get someone to check under it while you move the steering, try to pinpoint where its coming from.
good luck :wink: