'after a fashion' as an idiom means in some manner, but not very well, barely adequate. If you do something after a fashion, you do it but not very well, you almost do it but not completely.
* " I can paint ,but after a fashion. I am certainly not so good as you."
It means to some degree I can do it ,but not very well. It is relatively of a low order.
* "What she said is true after a fashion, although some of her statements were wrong."
Here what is said is almost true ,but not completely true.
* " I mended it ,after a fashion."
It is not completely mended or not without some flaws.