Sorry, as you probably suspect, this photo is too difficult to tell much. It's hard to get a sense of the colouration vs. light and even the general shape seems suspect (is it fluffed up?). I'm not hugely familiar with East African birds (though there is considerable overlap with southern Africa where I'm based), but I'm gonna say this one is stuck at passerine sp.
The people at BirdForum are great with African birds, but be warned, they can seem a bit mean spirited at times.