Fantasy novel from pre-1994

Cover had a girl in a cloak coming out of a castle door, all very grey. I believe she was training in magic but I may be wrong about that. it took place in a city that underwent a big revolution at the end. i also think the author's last name started with one of the last few letters of the alphabet at I remember having to go to the last fiction shelf at the library when i checked it out. I don't believe that it was by Jane Yolen as none of her covers/synopses seem familiar. Thanks in advance!

Instantly remembered the cover from your description, took me a few minutes to remember the actual title: Illusion.

Oh wow! Thanks so much; that's it!

A weird book, that one was.