In reply to Mr Whippy:
I think the Pass of Ballater is going to be your best bet I'm afraid.
If you don't know the crag the Western Sector is best suited for single pitch training, the middle tier is the usual spot.
I've done a fair bit of searching for any undeveloped crags near Braemar and there's nothing that really fits your description. If you can head into the hills many of the cairngorm crags are nice. There is single pitch on the top of Beinn Mheadhoin but it's a long way!
There are some undescribed crags on the Balmoral estate but not really suitable. Also, there are some boulders on the Invercauld Estate (described in the database) and the small quarry by the Inver hotel (also in the database) but I still think you'd be best heading to Ballater.
HTH